The True Science of Climate Change - October 2025 r8.pdf

Update of October 2023 edition including more details of The Water Cycle and world irrigation methods.

1. True Science of Climate Change – October 2025 1 of 28

The True Science of Climate Change
October 2025 [email protected]

Earth is a water planet: three-quarters of the surface is covered by water (NASA.)
Contents
1. Introduction 2
2. Planet Earth and Incoming Radiation from the Sun 2
3. Global Atmospheric Circulation 3
3.1 Jet Streams and El Nino 4
4. The Greenhouse Effect 4
4.1 Atmospheric Concentration of Carbon Dioxide 6
4.2 Environmental Impact of CO2 7
4.3 Coral Reefs 7
5. The Atmospheric Concentration of Water Vapour 8
5.1 The Physics of the Water Cycle including Latent Heat Transfer and Greenhouse Effect 9
6. World Population and Freshwater Withdrawals for Agriculture 10
6.1 Water Withdrawal Data 10
7. Reservoirs and Irrigation Methods for Agriculture 12
7.1 The Largest Man-made Lakes in the World 12
7.2 Paddy Fields 14
7.3 Irrigation by Canals 15
7.4 Centre-pivot Irrigation Systems 16
7.5 Drip Feed Irrigation 17
7.6 Media reports of World Crop irrigation 18
8. Evapotranspiration (& Condensation) of Water used for World Irrigation 18
8.1 Calculation of Annual Quantity of Latent Heat arising from Irrigation 19
8.2 Seasonal Irrigation 19
9. Observations of World Temperature Change 19
10. Observations of Polar Sea Ice 20
11. Observations of Southern Hemisphere Glaciers 22
12. Assessment of Climate Observations Relative to Expected Influence of Human Activities 22
12.1 Global Temperature Changes 22
12.2 Variation of Polar Sea Ice Extents 23
12.3 Southern Hemisphere Glaciers 24
13. Conclusions 24
14. Recommendations 25
Appendix - IPCC Reports on Water Vapour and associated Latent Heat 26

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The True Science of Climate Change.
1. Introduction
Observations of rising temperatures and more extreme weather phenomena, most likely caused by human
activities, have raised concern about climate change. The Intergovernmental Panel for Climate Change (IPCC)
Report AR4, issued in 2007, Chapter 1, Section 1.1 states: “Science is inherently self-correcting; incorrect or
incomplete scientific concepts ultimately do not survive repeated testing against observations of nature.”
This Study begins by describing the basic nature of planet Earth, its atmosphere and how the incoming energy
from the Sun is distributed over the surface (more than 70% water) to cause climate zones and weather
phenomena. It then examines two major processes affected by human activities that could cause the observed
changes to climate - these being:
(i) an increase in the atmospheric gases that absorb and re-emit long wave radiation. The result of reducing long
wave radiation back into space is called ‘The Greenhouse Effect’, and
(ii) an increase in the evaporation and condensation processes of ‘The Water Cycle’, in which global atmospheric
circulation transports water vapour and associated latent heat by convective and advective winds.
Observations of nature collated in this Study are by the Royal Meteorological Society, UK Meteorological Office,
the IPCC, US Universities, World Atlas, National Geographic, NASA, NSIDC, NOAA, ESA, NIWA, the UN Food and
Agriculture Organisation (FAO), and Sir David Attenborough at the BBC.
When assessed relative to the expected result of each of the above two processes, observations show that by far
the most important cause of climate change is increased atmospheric water vapour arising from crop irrigation
using at least 3,000 billion tonnes of water per annum, largely over normally semi-arid and desert land.
There are no observations of nature to justify the hypothesis that increased atmospheric content of carbon
dioxide and other trace gases, making up around 0.1% of the total, have an influence on climate.
2. Planet Earth and Incoming Radiation from the Sun

This photo is by NASA showing Earth’s surface dominated by water and clouds (condensed water vapour). Heat
arriving from the Sun by radiation at a given latitude varies during the year, largely due to the rotational axis of
the Earth being tilted 23.5 degrees to the plane of its orbit.

Radiation reaching the Poles is similar in the Arctic and the Antarctic. Both Poles have continuous sunlight for 11
weeks during their Summer, and continuous darkness for 11 weeks during their Winter.

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Total radiant energy arriving from the Sun has been estimated at 3,400,000 exajoules per year by Paul Breeze,
in Power Generation Technologies [Third Edition], 2019, and 120,000 terawatts or 3,780,000 exajoules, by Eric J.
Chaisson in his 2008 paper entitled ‘Long Term Global Heating from Energy Usage’.
According to BP’s Statistical Review of World Energy, the total energy used by humans for all their activities in
2019 was 583.9 exajoules (just 0.017% of the energy arriving from the Sun). Cities tend to be warmer than the
surrounding areas, especially in winter. However, the above-mentioned 2008 paper concludes that human activity
energy consumption has a negligible effect on Earth’s overall climate.
3. Global Atmospheric Circulation.
Incoming radiation warms the surface of the oceans and lands each day and allows cooling by night. Combined
with the rotation, the atmosphere reacts to produce a global circulation pattern of winds.
https://www.rmets.org/metmatters/global-atmospheric-circulation
Royal Meteorological Society quote: “Global circulation transfers energy from the tropics towards the poles. In the
northern hemisphere, warm moist air from the tropics moves northwards by the surface winds of the Ferrel cell.”
https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/global-circulation-patterns
UK Meteorological Office quote: “Global circulation provides a natural air conditioning system to stop the equator
becoming hotter, and poles becoming colder… Global circulation can be described as the world-wide system of
winds by which the necessary transport of heat from tropical to polar latitudes is accomplished. Warm, moist air
from the tropics gets fed north (and south) by the surface winds of the Ferrel cells.” (Named after American
Meteorologist William Ferrel in 1856).

Global Atmospheric Circulation contains warm, dry, high-pressure zones ~15
o
either side of latitudes 30
o
North
and South, creating arid and desert regions due to lack of rain, as shown in the sand-coloured areas in NASA’s
world map below. Much of the water vapour arising from the oceans and wetlands at these latitudes has been
carried poleward for hundreds of millions of years, and condenses to rainfall close to latitudes 60
o
N & S.

Winds in the Hadley Cells ensure that most water vapour there is driven towards the Equator to sustain jungle
vegetation in the Amazon, Congo and Borneo regions.

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The UK has a mild, wet climate due to prevailing South Westerlies from the Atlantic. Similar conditions exist at the
North-western coast of Canada near Vancouver. In the northern summer, easterly trade winds drive tropical
cyclone storms towards the south-eastern coasts of the USA and China.
3.1 Jet Streams and El Nino
The Jet Streams are high velocity streams of air located 9 to 16 km above Earth’s surface, and comprise the Polar
Front and Subtropical jet streams, both north and south of the Equator. The Jet Streams are very variable and
follow meandering courses, which can cause short-period changes to the weather close to Earth’s surface. The
path of jet streams affects cyclonic storm systems at lower levels in the atmosphere, so knowledge of their course
has become an important part of weather forecasting. For example, in 2007 and 2012, Britain experienced severe
flooding because the polar jet stayed south for the summer.

The El Nino – Southern Oscillation ENSO is the cycle of warm and cold sea surface temperature (SST) of the
tropical central and eastern Pacific Ocean. It has been noticed for thousands of years and can cause warm ocean
current along the west coast of South America in a cycle of every 2 to 7 years, occasionally reaching the Antarctic.
4. The Greenhouse Effect
Theories about certain atmospheric gases causing a ‘greenhouse effect’ that kept Earth’s climate warmer than it
would be without them started in the late 19th century. The two main greenhouse gases were identified as water
vapour (Tyndall 1861) and carbon dioxide (Arrhenius 1896), which restrict the escape of infra-red radiation back
into space from the daytime warned Earth, thus causing ‘radiative forcing’.
In 1975, Manabe and Weatherall at the US Princeton University published a research paper entitled: ‘The Effects
of Doubling the CO2 Concentration on the climate of a General Circulation Model’. Their computer simulations
(amongst others) showed that ‘increasing concentration of CO2 from 300 parts per million (ppm) to 600 ppm
raised the temperature of the model troposphere.’
In June 1988, Dr James Hansen, director of NASA's Goddard Institute for Space Studies, advised the US Senate
that the increase in atmospheric CO2 content from 280 parts per million (ppm) to 350 ppm (in 1988), caused by
combustion of fossil fuels, was causing climate warming.
Dr Hansen’s 1967 Ph.D. thesis concerned the atmosphere of Planet Venus, which is 96.5% CO2 and the pressure at
the rocky surface is 93 bar - 93 times the atmospheric pressure at the surface of Planet Earth. Venus takes 243
Earth days to rotate once. Dr Hansen theorised that the CO2 atmosphere acted to trap heat like a blanket and
caused a ‘runaway’ greenhouse effect.
Later in 1988, the UN created the Intergovernmental Panel for Climate Change (IPCC) which published its first
Scientific Assessment Report in 1990 under Chairman and Lead Editor, Dr John Houghton, then Head of the UK
Meteorological Office – now deceased.
The Policymakers Summary of the first IPCC Assessment Report AR1 1990 WG1, states: “The main natural
greenhouse gases are not the major constituents, nitrogen and oxygen, but water vapour (the biggest
contributor), carbon dioxide, methane, nitrous oxide and ozone.” Chapter 1 on Greenhouse Gases and Aerosols
states: “Tropospheric water vapour is the single most important greenhouse gas. but its atmospheric
concentration is not significantly influenced by direct anthropogenic emissions (human activities).”

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Sir John Houghton was knighted in 1991 and issued his book entitled: ‘Global Warming – The Complete Briefing’ in
1994. This book endorses Dr Hansen’s belief that increasing atmospheric CO2 content is the cause of climate
warming. It has been accepted by many as the ‘Bible’ on the subject.
Houghton’s influence over the content of the Summaries to Policymakers (SPMs) was to concentrate on
emphasising the role of CO2, methane and other trace gases (totalling less than 0.1% of the atmosphere) as
predicted by computer-modelling of climate. These computer models took little or no account of the effect of
farm irrigation on the atmospheric content of water vapour and the associated transfer of latent heat.
IPCC Report AR1 1990 WG1, quotes in italics.
Policymakers Summary
Under What natural factors are important?
Top of page xiv of 414: The main natural greenhouse gases are not the major constituents, nitrogen and oxygen,
but water vapour (the biggest contributor), carbon dioxide, methane, nitrous oxide and ozone.
Note: Since year 1900, humans have constructed at least 200,000 DAMS over 15m height, largely to create
reservoirs of freshwater for distribution over fields of crops sown in relatively dry areas of land.
Chapter 1. Greenhouse Gases and Aerosols
Page 7 Section 1.1 Introduction Tropospheric water vapour is the single most important greenhouse gas. but its
atmospheric concentration is not significantly influenced by direct anthropogenic emissions (human activities).
Note: The IPCC chose to ignore the effect of humans distributing 2,500 billion tonnes of irrigation water over crops
grown in largely semi-arid and desert land in the year 1990 - see the UN FAO graph on page 11 here.
Page 320 Section 11.2 3 Precipitation and Evaporation
The condensation of water is the main energy source of the atmospheric heat engine (by release of its latent heat)
and the transport of water vapour by the atmospheric circulation is a key process in the redistribution of the Sun’s
energy in the Earth system. Water vapour is also an important greenhouse gas.
The diagram below of the ‘Greenhouse Effect’ is from IPCC Report AR1 dated 1990, Policymakers Summary, page
22 of 414.

The left-hand side of the diagram is dominant during the day. During the night, infra-red radiation from the
warmed surface is absorbed and re-emitted by the greenhouse gases and clouds, shown on the right-hand side.

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IPCC Report AR2 1995 Chapter 3. Observed Climate Variability and Change
Page 161 Section 3.3.7. “Water vapour is the most abundant greenhouse gas and makes the largest contribution
to the natural greenhouse effect.”
IPCC Report AR3 2001 Chapter 1: The Climate System: An Overview
Bottom left of page 88 Section 1.1.2 “The most variable component of the atmosphere is water in its various
phases such as vapour, cloud droplets, and ice crystals. Water vapour is the strongest greenhouse gas. For these
reasons, and because the transition between the various phases absorbs and releases much energy (latent heat),
water vapour is central to the climate and its variability and change.”
In 2010, NASA GISS staff published a paper entitled: ‘Attribution of the present-day total greenhouse effect’, which
reduced their emphasis on the role of CO2, and concluded, quote: “water vapour is the dominant contributor
(~50% of the effect), followed by clouds (~25%) and CO2 (20%).”
IPCC Report 2013 FAQ 8.1 states: “The contribution of water vapour to the natural greenhouse effect relative to
that of carbon dioxide (CO2) depends on the accounting (computer analysis) method but can be considered to be
approximately two to three times greater.”
The IPCC Summaries for Policymakers largely ignore their Report observations of increased water vapour and
Northern Hemisphere precipitation, see the Appendix on pages 21 to 23 here.
Some Climatologists, some reporters of the Media, and some fervent environmentalists have presented the
hypothesis that increasing atmospheric carbon dioxide content is the main cause of climate change so strongly
that more than 90% of people believe it to be true. Some Environmentalists, and some city dwellers, use this
belief to justify restriction of road and aircraft traffic, and further oil and gas field development.
4.1 Atmospheric Concentration of Carbon Dioxide

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The records kept by the Scripps Institution of Oceanography in San Diego and NIWA (New Zealand National
Institute of Water and Atmospheric Research) show that the atmospheric content of CO2 at the South Pole, and at
Mauna Loa in Hawaii (at latitude 20 degrees North), are similar. CO2 concentration has increased equally
worldwide from 315ppm in 1960 to 427ppm (0.0427%) in 2025. CO2 makes up LESS THAN 1 PART IN 2,000
(0.05%) of the atmosphere.
Atmospheric Carbon Dioxide over Geologic Time

There has historically been much more CO2 in Earth’s atmosphere than exists today. For example, during the
Jurassic Period (200 million years ago), average CO2 concentrations were about 1800 ppm or about 4.7 times
higher than today, providing lush vegetation to sustain giant dinosaurs.
4.2 Environmental Impact of CO2
The first fish evolved over 500 million years ago, and ammonites, the largest shellfish fossils, first appeared 420
million years ago. Both species were not harmed by CO2 concentrations greater than 3000 ppm.
CO2 is a basic requirement for photosynthesis and is therefore food for phytoplankton and all plants.
Horticulturalists raise the CO2 concentration to 1000 ppm in greenhouses to improve crop yield. The UK Health
and Safety Executive (H&SE) allows concentration up to 5000 ppm for 8-hours in a work environment.
4.3 Coral Reefs
https://www.theguardian.com/environment/2021/feb/18/great-barrier-reef-found-to-be-in-failing-health-amid-
calls-for-urgent-action
The Guardian, February 2021 quote: “The Queensland government says dissolved inorganic nitrogen - originating
from farm fertilisers - is linked to algal blooms, outbreaks of coral-eating starfish and coral disease at the Great
Barrier Reef.”
Dr Lissa Schindler, Great Barrier Reef campaigner at the Australian Marine Conservation Society, said: “Improving
water quality needs the support and dedication of all farmers and graziers in Queensland and they’ll need backing
from the Queensland government to adopt the best practices required,” Schindler said. “That’s why we are calling
for more funding to help the agricultural sector comply quickly with the regulations.”

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5. The Atmospheric Concentration of Water Vapour
Reference: https://gml.noaa.gov/education/info_activities/pdfs/TBI_earths_atmosphere.pdf
Quote “Composition of the Present Atmosphere
The atmosphere is composed of a mix of several different gases in differing amounts. The permanent gases whose
percentages do not change from day to day are nitrogen, oxygen and argon. Nitrogen accounts for 78% of the
atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are
TRACE GASES that account for about a tenth of one percent of the atmosphere.
Water vapor is unique- its concentration varies from 0-4% of the atmosphere depending on where you are and
what time of the day it is. In the cold, dry artic regions water vapor usually accounts for less than 1% of the
atmosphere, while in humid, tropical regions water vapor can account for almost 4% of the atmosphere (nearly
100 times the concentration of CO2) Water vapor content is very important in predicting weather.”
A 1976 University of Illinois Report entitled ‘The Effect of Irrigation on Precipitation in the Great Plains’ states: ‘It
has been demonstrated that there has been an increase in the rainfall in and surrounding the irrigated regions
during the same period that the growth of irrigation has occurred.’
IPCC 2013 AR5 WG1 Chapter 8.3.5.5 refers to a 2010 paper by NASA personnel and states, quote: “Irrigation in
the Great Plains in the summer produced enhanced precipitation in the Midwest 1000 km to the northeast.”
In a 2005 paper by Line J. Gordon (of Stockholm) and others entitled: ‘Human modification of global water vapor
flows from the land surface’ the authors state, quote: “It is well known that irrigation is, by far, the largest water
user in terms of liquid water withdrawal from rivers and aquifers, and that human modification of the hydrological
cycle has profoundly affected the flow of liquid water across the Earth’s land surface.”
Petra Doell (of Frankfurt) was thanked for providing the estimate of vapour flow that is noted in Figure 3 of the
paper, quote: Additional local water vapor flows due to irrigation (mmyr), defined as the change in vapor flows
when irrigation is added to actual vegetation. The total increase in vapor flows amounts to 2,600 km
3
/year (2,600
billion tonnes/year).” Note that 1 km
3
of water weighs 1 billion tonnes.
http://earthguide.ucsd.edu/virtualmuseum/climatechange1/09_1.shtml
University College of San Diego quote: “The heat expended in phase change of water to vapor (by releasing the
hydrogen bonds) is not lost but is contained in the vapor in latent form. When the vapor condenses (to re-connect
the hydrogen bonds), the heat is freed for warming the surrounding air.”
https://earthobservatory.nasa.gov/features/Water
The Water Cycle by Steve Graham, Claire Parkinson, and Mous Chahine published October 1, 2010
NASA quote: “Water vapor is a powerful greenhouse gas, and it is a major driver of the Earth’s weather and
climate as it travels around the globe, transporting latent heat with it.
While evaporation from the oceans is the primary vehicle for driving the surface-to-atmosphere portion of the
hydrologic cycle, plant transpiration on land is also significant. For example, a 1-acre cornfield can transpire as
much as 4,000 gallons of water every day.”
https://www.worldatlas.com/articles/what-is-the-environmental-impact-of-
irrigation.html#:~:text=Increased%20evaporation%20in%20irrigated%20areas%20can%20cause%20instability,hav
e%20an%20indirect%20impact%20on%20the%20surrounding%20environment.
World Atlas quote (dated 2017): “Increased evaporation in irrigated areas can cause instability in the atmosphere
(for example, violent thunderstorms), as well as increase levels of rainfall downwind of the irrigation. These
changes to the climate are a direct result of changes to natural moisture levels in the surrounding atmosphere."
https://education.nationalgeographic.org/resource/environmental-impacts-agricultural-modifications/
National Geographic quote (June 2022): “Recent studies have confirmed that cropland irrigation can influence
rainfall patterns not only over the irrigated area but even thousands of miles away.”
Like the IPCC Report SPMs, the National Geographic and World Atlas references contain no mention of the
transfer of latent heat that always occurs between the locations of evaporation and condensation.

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In his 2001 paper ‘Concepts of the Water Cycle’, Irish hydrologist James Dooge included a 1987 diagram by
Gunther Garbrecht of Holland as Figure 3. It showed the water cycle acting from the sea, to form clouds in the
immediate sky, to rain over hills, and rivers back to the sea. The following diagram is a modified version to show
latent heat transfer.
5.1 The Physics of The Water Cycle including Latent Heat Transfer and Greenhouse Effect.

1. Water evaporates from the sea and also from rivers, lakes, reservoirs and wet land. Evaporation over land areas
has greatly increased since year 1900. mainly due to IRRIGATION of crops (rice paddies are very water intensive),
vineyards, parks, gardens, and golf courses - often located in normally hot, dry areas.
Freshwater supply for irrigation has been increased by installing dams to create artificial lakes (reservoirs) and by
drilling to extract water from underground aquifers. At least 200,000 dams with height greater than 15m have
been installed worldwide since year 1900. Cool winter rains are stored in reservoirs before distribution over crops
growing in warm spring and summer soils. The UN FAO and the World Resources Institute estimate that
freshwater withdrawals used for agriculture have increased from 1,000 billion tonnes per year in 1940 to more
than 3,000 billion tonnes per year since 2000.
2. The surface area of evapotranspiration is cooled by the phase change of liquid to gas which absorbs latent heat
energy (2,400 kJ/kg at 30C) to break intermolecular hydrogen bonds. Once airborne, the invisible water vapour
becomes the most important greenhouse gas (as defined in all IPCC Reports), with major capacity to prevent the
escape of infra-red radiation from warmed land into space - especially during the night. Air at 30
o
C can contain
around 3% water vapour without condensing. Winds are very variable but have been noted to flow in the pattern
of Global Atmospheric Circulation, see section 3 of this document.
3. Clouds (condensed water vapour) may form by convection to cooler air above the evaporation area, or they
may form far downwind by advection when the air with increased water vapour rises over hills or arrives/rises in
cooler latitudes/altitudes. Clouds increase the greenhouse effect by restricting the escape of infra-red rays to
space. It is a very common observation that cloudy-sky-nights stay warmer than clear-sky-nights. At 10
o
C, water
vapour condenses when atmospheric content exceeds 1%, resulting in more cloud formation and precipitation
(rain or snow) during winter.
4. When water vapour condenses, it releases its latent heat energy to warm the normally cool surrounding
atmosphere. This can generate calm dark rainclouds, or more violent thunderstorms & tornadoes, and can melt
ice/permafrost, depending on the quantity and rate of energy released. Intense condensation over the ocean
combined with Jet Stream and Coriolis Effects causes tropical cyclones (hurricanes or typhoons).

The Water Cycle

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6. World Population and Freshwater Withdrawals for Agriculture

In 1960, world human population was 3 billion. At the end of 2024 the population was 8.2 billion.
Approximately 90% of people live in the Northern Hemisphere.
6.1 Water Withdrawal Data.

• The chart above, from a 2020 paper by the World Resources Institute, shows 3,200 km
3
used for irrigation
over the years 2000 to 2014.
Reference: https://www.wri.org/insights/domestic-water-use-grew-600-over-past-50-years
• Note that water withdrawn from underground aquifers adds to the rise in sea level, following
evapotranspiration, condensation and runoff.

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The United Nations Food and Agriculture Organisation (FAO) noted the vast increase in freshwater
withdrawals over the years 1900 - 2010. https://www.fao.org/aquastat/en/overview/methodology/water-use
UN FAO Quote: “The chart below shows global water withdrawal over time, including (in addition to the water
withdrawal for Agriculture, Industries & Municipalities) the evaporation from Reservoirs, which are artificial
lakes created when a dam is built. 300 billion tonnes of water evaporated from their surface areas in 2010.
While this is not a water withdrawal per se, it should be considered as an anthropogenic consumptive water
use, since this evaporation would not take place without the human intervention of building a dam to store
freshwater resources for different purposes, such as for withdrawal by one of the above sectors, for generating
electricity (hydropower), etc.”

In his 2002 program entitled 'Food for Thought' (last episode of series 'Life of Mammals' for BBC TV), Sir David
Attenborough (then aged 76) warned that, due to increased population, humans were diverting the equivalent
content of entire rivers to irrigate crops that covered more than a third of the world’s land surface.



He walked with an umbrella under a centre-pivot irrigation system in the Arizona desert (shown above) and stated
that the rich diversity of the natural landscape has been converted to uniformity - complex communities have
been changed to monocultures. At the end, he advised that: “Perhaps it is time to control the population (then
6.2 billion) to allow the survival of the environment.”

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7. Reservoirs and Irrigation Methods for Agriculture

https://www.worldatlas.com/articles/the-largest-man-made-lakes-in-the-world.html
Human-made Lakes
Some of the earliest dam reservoirs were constructed about 4000 years ago in Egypt, China, and Mesopotamia
and their primary purposes were irrigation and supply of drinking water. However, there were no very large dams
in the world before year 1900. Requirements may now include commercial fisheries, power generation, industrial
and cooling water supplies, commercial sports, and other recreational activities.
7.1 The Largest Man-made Lakes in the World.

Note that 6 of the 15 are listed in Russia and 4 are in Canada.
The Hoover Dam was constructed on the Colorado River at latitude 36
o
N between 1930 and 1936. It is the highest
concrete arch dam in the USA and impounds the Lake Mead reservoir, which extends for 115 miles upstream.
There are 15 secondary dams along the Colorado River. They help supply water to the cities of Denver, Salt Lake
City, Phoenix, Las Vegas and Los Angeles, together with irrigating at least 6 million acres of farmland.
The Three Gorges Dam on the Yangtse River at 31
o
N in China was constructed over the years 1994 to 2012. It is
2,335 m (7,661 ft) long and the top of the dam is 185 m (607 ft) above sea level. The dam reservoir is on average
about 660 km (410 mi) in length. It contains 39.3 km
3
of water with total surface area of 1,045 km
2
(403 sq. mi). The Largest Man-Made Lakes In The World
RankReservoir Volume km³River Dam Country Year
1Lake Kariba 180.6Zambezi RiverKariba Dam Zambia/Zimb. 1959
2Bratsk Reservoir 169Angara River Bratsk Dam Russia 1964
3Lake Volta 150Volta River Akosombo Dam Ghana 1965
4Manicouagan Reservoir 141.8Manicouagan RiverDaniel-Johnson Dam Canada 1968
5Lake Guri 135Caroní River Guri Dam Venezuela 1986
6Lake Nasser 132Nile River Aswan High Dam Egypt 1971
7Williston Lake 74.3Peace River W. A. C. Bennett DamCanada 1967
8Krasnoyarsk Reservoir 73.3Yenisei RiverKrasnoyarsk Dam Russia 1967
9Zeya Reservoir 68.4Zeya River Zeya Hydroelectric StationRussia 1978
10Robert-Bourassa Reservoir 61.7La Grande RiverRobert-Bourassa gen. stn.Canada 1981
11La Grande-3 Nord Reservoir 60La Grande RiverLa Grande-3 gen. stn.Canada 1981
12Ust-Ilimsk Reservoir 59.3Angara River Ust-Ilimsk Dam Russia 1977
13Boguchany Reservoir 58.2Angara River Boguchany Dam Russia 1989
14Kuybyshev Reservoir 58Volga River Zhiguli Hydroelectric Stn.Russia 1955
15Cahora Bassa 55.8Zambezi RiverCahora Bassa Dam Mozambique 1974

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World Distribution of Major Reservoirs - note mainly located in the Northern Hemisphere.
Reference: https://www.nature.com/articles/s41597-024-03752-9/figures/1

Global Dam Watch is an international collaboration which aims to provide open access data and tools focused on
existing dams and reservoirs, and those that are planned to be built. Data accuracy depends on each country’s
willingness to register the information and may not be complete.
https://www.globaldamwatch.org/intelligence
GDW intelligence (GDW-i) is a knowledge system providing live dam mapping, curation, research, analysis and
visualisation tools for data. It allows addition and editing of dam data by country and basin and also supports
analysis, visualisation and download of data. GDW-i also provides a suite of analytical tools in support of policy
and decision making. Scroll down to the message “Click the image below to enter GDW-i.” After changing to
www2.policysupport.org that gives access to the records of each country - click on Submit..
United States of America - 60,344 registered dams on 10/Nov/2022. Those flagged red are most recently added.

Registered numbers of dams in other countries include China 15,461; India 9,539; Brazil 7,713; South Africa,
7,700; Australia 5,518.

14. True Science of Climate Change – October 2025 14 of 28
7.2 Paddy Fields
Many dam reservoirs provide water for growing rice. The scene below of water vapour over flooded paddy fields
is from Program 2 of the 3-program TV series by PBS/WGBH entitled: ‘H2O the Molecule that Made Us’. During
the program the commentator advises “The way we control water is changing the planet” and that “China has
87,000 dams and the USA has 84,000.” These quantities may not have been registered with GDW.

Flooded rice paddies are particularly water dependent. Each kilo of rice takes about 2000 litres of water to
produce. The 2021 TV Series ‘Age of Humans’ by the Smithsonian Channel advised quote: “Rice paddies are the
main source of nutrition for half the population of the planet (now 8.2 billion).”

China India


Bali China

15. True Science of Climate Change – October 2025 15 of 28
7.3 Irrigation by Canals – example in Pakistan
Reference: https://www.internetgeography.net/topics/the-indus-basin-irrigation-system-case-study/

Large parts of Pakistan and the regions covered by the Indus Basin have an arid or semi-arid climate. The rainfall in
these areas is low and erratic, which is insufficient for the agriculture that most of the population depends on for
their livelihood. The system was required for effective water management. It ensures that water could be stored
during times of surplus (during monsoons or heavy snow melt) and used during times of scarcity.



Waterlogging and Salinity: Over-irrigation can lead to waterlogging and salinity problems in the soil, making it
less fertile and productive. This is a significant issue in the Indus Basin.
Evaporation: High temperatures in the summer result in significant water loss through evaporation.
Environmental Impact: Dams disrupt the natural flow of rivers, impacting aquatic ecosystems and sometimes
causing biodiversity loss. The irrigated area raises the humidity of the local atmosphere which can enhance any
storm activity and flooding.
Sedimentation: Dams in the IBIS trap sediment which would naturally fertilize fields downstream. Over time, this
can decrease soil fertility downstream while reducing the dam’s water storage capacity due to sediment build-up.
Maintenance Costs: The upkeep of large infrastructure like dams and canals can be expensive. These costs often
rise as the infrastructure ages.
Population Displacement: The construction of large dams and canals often requires the displacement of local
populations, causing social and economic disruptions.

Text extracted from the website: The Indus River,
originating high in the Tibetan Plateau, flows roughly
from north to south through the length of Pakistan
before culminating in the Arabian Sea. The river,
nurtured by intense rainfall and snowmelt from the
mountains, supplies the water necessary for irrigating
the arid agricultural lands in the south.
The Indus Basin Irrigation System (IBIS) is the largest
unbroken irrigation network worldwide. It incorporates
three large dams and more than 100 smaller dams that
manage the water flow. Twelve link canals facilitate the
transfer of water between rivers. The system extends
over 64,000 km of minor canals that distribute the water
throughout rural areas. The IBIS provides water to over
1.6 million km
2
of Pakistan’s agricultural land.
Large dams within the system, such as the Tarbela (at
right) and Mangla, also generate hydroelectric power,
contributing to the country’s energy needs.
The IBIS significantly contributes to the economy by
supporting agriculture, a major part of Pakistan’s GDP.
The canal system plays a critical role in maintaining
food security for Pakistan by enabling the cultivation
of various crops throughout the year. It also supports
industries like textiles that rely on agricultural
products.

Disadvantages

16. True Science of Climate Change – October 2025 16 of 28
7.3 Centre-pivot Irrigation Systems
Centre-pivot irrigation systems were developed for use in the mid-west of the USA. Farmers withdraw water by
drilling wells into the Ogallala underground aquifer and use pumps to raise it to the surface. When installed near a
river reservoir, such as on the Nile in Egypt and the Dnieper in Ukraine, the water is withdrawn through surface
pipelines or canals.

Since 1940, vast areas of normally semi-arid or desert land have been converted to crop production to feed the
ever-increasing world population. Atmospheric water vapour is increased by evaporation from damp soil, and by
transpiration from plant leaf stomata.

Irrigation Circles near Imperial, Nebraska, USA (left) and Kakhovka, Ukraine (right)

Irrigation circles at Wadi as Sirhan, Saudi Arabia (left). The Toshka Lakes Project near the Aswan Dam, Egypt
(right) uses water from Lake Nasser. Evaporation of water from Lake Nasser in 2007 (excluding Toshka Lakes and
irrigation circles) was estimated at between 10 and 16 billion tonnes per year.

17. True Science of Climate Change – October 2025 17 of 28
7.4 Drip Irrigation.
Wikipedia quote: “Irrigation in viticulture is essential to wine production. In the physiology of the grapevine, the
amount of available water affects photosynthesis and hence growth, as well as the development of grape berries.
While climate and humidity play important roles, a typical grape vine needs 25-35 inches (635-890 millimetres) of
water a year, occurring during the spring and summer months of the growing season, to avoid stress.

The system that provides the most control over water management is drip irrigation. Long plastic water supply
pipes that run down each row of vines in the vineyard so that each individual grape vine has its own individual
dripper. With this system, a viticulturist can control the precise amount of water that each grapevine needs.”

Google Earth Pro website allows a User to see vineyard layouts around the world. The left-hand picture here is of
Hardys Winery and nearby vineyards in Australia, while the right-hand view shows vineyards in South Africa. Large
areas of Chile and Argentina have been covered in drip feed irrigated vineyards over the last 30 years.

Artificial rainwater obtained from dam reservoirs and aquifers for irrigating Spanish vineyards increased 9 times
between the years 1992 and 2012. The above satellite image of the area west of Valencia shows the Utiel-Requena
Aquifer (light brown area at left) which measures approximately 30km x 20km. Water storage is provided by the
110m high Benageber Dam and the 129m high Contreras Dam. The area contains thousands of vineyards and olive
groves installed with drip or subsurface irrigation pipes, leading to local high atmospheric humidity and saturated
soil unable to absorb heavy rainfall. These conditions very likely contributed to the severe storm, flash flooding and
raging torrent rivers in October 2024, which killed more than 230 people and did £15 billion worth of damage.

18. True Science of Climate Change – October 2025 18 of 28
7.5 Media Reports of World Crop Irrigation
New York Times Report on the ‘Irrigation Juggernaut’, September 2010, stated, quote: “Anyone who has flown
over the American West on a clear day has probably noticed the enormous effect that irrigated farming has had
on the landscape of the country. Fields of corn, potatoes and other crops can be seen dotting land that would
otherwise be semi-desert, and the spray from some types of irrigation systems creates perfect circles of green in
these parched landscapes.” Standard diameters are half mile, one kilometre, or one mile.
The Guardian article, May 2012, entitled ‘Fresh water demand driving sea-level rise faster than glacier melt’
states, quote: “Trillions of tonnes of water have been pumped up from deep underground reservoirs in every part
of the world.”
The Physics Today article, November 2016, entitled ‘Land’s complex role in climate change’ states, quote: “The
irrigation of semi-arid land can dramatically alter a region’s water balance. Due to the combined effects of
evaporation and transpiration, collectively termed evapotranspiration, increases in ground moisture tend to raise
humidity in the overlying atmosphere. Such increases in humidity can mean the difference between a mild
shower and a torrential downpour.”
8. Evapotranspiration (& Condensation) of Water used for World Irrigation

Source: USGS/Salinity Management Organisation Image from www.shoalwater.nsw.gov.au
The total vapour flow from irrigation is the combined quantity from soil and plant leaves called
‘evapotranspiration’. North Carolina State University explained, quote:
“The Evaporation in evapotranspiration refers to water evaporated from over land. This includes evaporation
from soil, wetlands, and standing water from places like roofs and puddles. It can also refer to direct evaporation
of liquid water from the leaf surface of the plant.
Transpiration happens when plants release water vapor from tiny holes, called stomata, in their leaves. This is
caused in part by the chemical and biological changes that occur as the plant undergoes photosynthesis and
converts carbon dioxide into oxygen. Plants transpire up to 99% of the water absorbed by their roots to cool
down their leaves, thus performing the same function as a human sweating. The picture above shows the stomata
on the underside of the leaf releasing water vapor (blue arrow) because of the warmth from the sun.”
8.1 Calculation of Annual Quantity of Latent Heat arising from World Irrigation
The total of water used for crop irrigation is approximately 3,000 billion tonnes p.a., see section 6 above. Around
90% of it is converted to 2,700 billion tonnes of water vapour by radiant heat from the sun.

The energy required from the Sun per year to evaporate water on the ground and inside plant leaves for
transpiration is therefore the weight of water transformed to vapour multiplied by the latent heat of evaporation,
at say 30C, which is: 2,700 x 10
12
kg x 2.400 x 10
6
J/kg = 6,480 exajoules/year.

This quantity is more than 10 times the energy consumed for all other human activities, including domestic
heating, industry and transport, as noted on page 3. Due to most crop irrigation being done during summer in the
Northern Hemisphere above latitude 20
o
N, around 75% of this total water vapour and associated latent heat
energy is carried poleward by atmospheric circulation in the Ferrel Cells.

19. True Science of Climate Change – October 2025 19 of 28
On reaching cooler altitudes or latitudes, the extra vapour from irrigation condenses to release its latent heat,
leading to increased cloud formation, ~1,800 billion tonnes of extra Northern Hemisphere rain, more violent
storms, reduced permafrost, and melting Polar and Himalayan ice.
8.2 Seasonal Irrigation
Irrigation is a seasonal activity that concentrates on Spring and Summer periods between latitudes 20 and 60
degrees, both north and south. Most humans live at these latitudes, and they are responsible for increased
irrigation to meet food and vineyard demand. Large increases in irrigation have been applied to farmland and
vineyards over the last 30 years.
9. Observations of World Temperature Change.
In 2007, World Temperature Changes were published in IPCC Report AR4 WGII: Climate Change 2007 – Impacts,
Adaptation and Vulnerability. The map below is copied from page 4 of 16 of the Summary for Policymakers.
https://www.ipcc.ch/report/ar4/wg2/summary-for-policymakers/


Figure SPM.1. Locations of changes in average annual surface air temperature over the period 1970-2004,
showing mainly Northern Hemisphere warming, with slight cooling in the Antarctic area.
In 2017, NASA’s similar map used data from 6,300 land and marine-based stations. It shows Earth’s average global
temperature from 2013-17, as compared to a baseline average from 1951 to 1980. Ref:
https://www.nasa.gov/press-release/long-term-warming-trend-continued-in-2017-nasa-noaa

The temperature changes noted in the IPCC 2007 map were confirmed by NASA in 2017.
• Northern areas have experienced warming of more than 2 degrees F (~1.1 deg. C).
• Large areas below 50 degrees South have cooled by 0.5 to 1 degree F.

20. True Science of Climate Change – October 2025 20 of 28

In March 2021, the NOAA published a world temperature change map for the years from 1990 to2020, Ref:
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Increasing temperatures were observed over higher northern latitudes. Temperatures were lower in areas south
of 45
o
S – very similar to the results noted by the IPCC in 2007 and NASA in 2017.
There have been no long-term observations of complete global warming.

10. Observations of Polar Sea Ice.
The NSIDC and NOAA websites state: “The polar regions are the most sensitive areas to climate change on Earth”,
see https://nsidc.org/cryosphere/seaice/index.html and https://oceanservice.noaa.gov/facts/sea-ice-climate.html
The NSIDC publishes results from satellite observations by NASA of Arctic and Antarctic Sea Ice Extent.

NASA issued a summary of Antarctic Sea Ice Extent on 16
th
September 2016:
see https://earthobservatory.nasa.gov/features/SeaIce
NASA Quote: “Since 1979, the total annual Antarctic Sea Ice Extent has increased about 1 percent per decade.
For three consecutive Septembers (2012 to 2014), satellites observed new record highs for winter sea ice extent
around Antarctica. The largest of those occurred in September 2014, when the ice reached 20.14 million square
kilometres (7.78 million square miles).
You might wonder how Antarctic Sea ice could be increasing while global warming(?) is raising the planet’s
average surface temperature. It’s a question that scientists are asking, too.”

21. True Science of Climate Change – October 2025 21 of 28
NASA/NSIDC Graphs of Polar Sea Ice Extent cover the 46-year period from 1979 to date.
Reference: https://nsidc.org/sea-ice-today/sea-ice-tools/charctic-interactive-sea-ice-graph


In 2001, the extent of Arctic Sea Ice, shown by the continuous red line, was very close to the 1981-2010 Median.
The major reduction to 3.4 million km
2
in the summer of 2012 (dotted red line) was a serious cause for concern.
However, minimum extent in September 2025 (blue line) recovered to 4.6 million km
2
, even though atmospheric
CO2 concentration had risen to 422ppm from 390ppm (this is contrary to CO2-warming theory).


The winter extent of Antarctic Sea Ice increased gradually over the period from 1979 to 2014, reaching a
maximum of 20.14 million km
2
, shown by the continuous red line. In a public lecture dated 2012, a senior NASA
scientist noted that this increasing extent of Antarctic Sea ice was contrary to CO2-warming theory. In 2020 and
2021, winter extent slightly exceeded the 1981-2010 Median extent (as shown by the light blue and mauve lines).
The 1979 - 2025 low of 17 million km
2
in 2023 – due to a major El Nino event in the Pacific Ocean and probably
aided by increased Southern Hemisphere irrigation - has recovered to 17.8 million km
2
in 2025 (darker blue).

22. True Science of Climate Change – October 2025 22 of 28
11. Observations of Southern Hemisphere Glaciers
New Zealand

Observations carried out by scientists from Victoria University of Wellington and NIWA, were reported in the
scientific journal Nature Communications.
https://www.wgtn.ac.nz/news/2017/02/explaining-new-zealands-unusual-growing-glaciers
Quote: “At least 58 New Zealand glaciers advanced between 1983 and 2008, with Franz Josef Glacier at 43
degrees South (Kā Roimata o Hine Hukatere) advancing nearly continuously during this time……lower
temperature caused the glaciers to advance, rather than increased precipitation as previously thought.”
Chile and Argentina
The European Space Agency (ESA) presented evidence in 2016 showing that, unlike receding Northern
Hemisphere glaciers, the Pio XI (Bruggen) Glacier in southern Chile at latitude 49degS advanced over the previous
60 years.
The Perito Moreno Glacier located in southern Argentina at 50.5degS has been advancing and is now stable.
These observations add evidence that climate temperatures were not increasing in the Southern Hemisphere.
12. Assessment of Climate Observations Relative to Expected Influence of Human
Activities.
Atmospheric CO2 content arising from combustion of fossil fuel has been steadily increasing worldwide from
0.03% to 0.042% now. It is still less than 1 part in 2,000 (0.05%). Its concentration peaks during winter due to
domestic heating and reduced photosynthesis. Its influence on climate is not detectable from long-term
observations of changes to world temperatures, polar sea ice extents and southern hemisphere glaciers.
Increased atmospheric water vapour (above the normal 1% to 3% of the atmosphere) caused by
evapotranspiration from irrigated crops is largely active during spring and summer periods. It is the most
important greenhouse gas while uncondensed (invisible), adds to the greenhouse effect as clouds, and it transfers
its latent heat to the location where it condenses to rain or snow.
12.1 Global Temperature Changes
All records of world temperature changes over periods from 1950 to 2020 show greatest increases in high
northern latitudes, and slight reduction in latitudes south of 45
o
S. There are no records of uniform global
warming. The atmospheric concentration of CO2 is practically similar worldwide, and if it does have an influence
on climate warming, there should be evidence of at least some temperature increase in both polar areas.

23. True Science of Climate Change – October 2025 23 of 28
World human population is distributed with around 90% living in the Northern Hemisphere, giving rise to a similar
percentage of total crop irrigation. The annual application of ~2,700 billion tonnes of irrigation water is largely
done in the high-pressure zone of global atmospheric circulation, which extends from latitudes 15
o
N to 45
o
N.
Water vapour with associated latent heat arising from this irrigation is carried towards the Arctic region by winds
in the northern Ferrel Cell. As it travels north, the land beneath the increased water vapour retains more of its
daytime-acquired-heat due to the enhanced greenhouse effect of extra uncondensed water vapour. In cooler
atmospheric conditions, the vapour condenses to release its latent heat and falls as increased rain or snow.
Observed long-term global temperature changes are exactly as expected from mainly Northern Hemisphere
increased crop irrigation. There is no correlation with worldwide atmospheric CO2 increase.
Most notifications of climate change refer to heat waves or flooding during the summer period of both
Hemispheres. This indicates that climate change is most likely related to a summer activity. CO2 concentration
tends to peak during the winter period and falls during the spring and summer due to absorption of CO2 by
photosynthesis for plant growth.
In winter of 2021, there was a record low temperature of -20.6C in Slovenia. In January 2023, there was a record
low of -53C in Mohe, China. Any warming of planet Earth is mainly noticed in summertime when water vapour
from irrigation is a maximum and CO2 concentration is a minimum.
Reports of global increased temperature refer to the annual average temperature. Full assessment of the records
shows that most increase has occurred to summer nighttime minimum temperatures. IPCC 1995 AR2 WG1
contains section 8.5.3 Diurnal Temperature Range (DTR), quote: “Several studies in Chapter 3 reported that, since
the 1950s, minimum (night) temperatures have increased two to three times faster than maximum temperatures
over large areas of land in the Northern Hemisphere. The result is a reduction in DTR, especially during summer
and autumn.” The greenhouse effect of water vapour restricts the escape of infra-red waves from daytime
warmed Earth, so raised summer night temperatures are consistent with the activity of crop irrigation.
12.2 Variation of Polar Sea Ice Extents
Observed variations of Polar Sea Ice Extents are as expected from mainly Northern Hemisphere increased crop
irrigation during summers. There is no correlation with worldwide atmospheric CO2 increase.
Arctic
NASA/NSIDC’s satellite observations of Polar Sea Ice Extents, starting in 1979, show a significant reduction in
Arctic summer Sea Ice from around 7 million km
2
to the all-time minimum of 3.4 million km
2
in 2012. However, in
the September of 2025, the minimum summer extent was recorded as 4.6 million km
2
– an unexpected increase
of 35% over the 2012 minimum.
The winter Extent over 44 years showed less significant reduction from 16 to 14.5 million km
2
.
These results comply with crop irrigation mainly confined to spring and summer periods, with less water being
available since 2012 due to underground aquifers running dry and use of more efficient irrigation methods.
Atmospheric CO2 content is highest in winter due to domestic heating requirements, so its effect should be less in
summer than winter. There should be no recent recovery of summer extents because CO2 content has increased
from 390ppm in 2012 to 425ppm in 2024.
Antarctic
Over the 35 years between 1979 and 2014 Antarctic Sea Ice Extent increased, with 2012, 2013 and 2014 having
increased maximum summer and winter extents year on year. This most likely indicated that the Southern Ocean
around the continent was cooling, while CO2 concentration increased worldwide from 335 to 395ppm.
Antarctic Sea Ice Extent in 2020 and 2021 slightly exceeded the 1981-2010 Median.

24. True Science of Climate Change – October 2025 24 of 28
However, during the Southern winter of 2023, peak Antarctic Sea Ice Extent was a record low at 16.95 million km2
on 9
th
September. This compares to the previous lowest on the NSIDC records of 17.96 million km2 of 1986.
The El Nino phenomenon was particularly strong in 2023, with a warm current running down to Antarctica. It is
likely that heat energy delivered by El Nino worked in combination with increased latent heat transfer from
Southern Hemisphere irrigation to produce an exceptional reduction in Sea Ice Extent.
The winter extent in September 2025 has recovered to 17.8 million km2
12.3 Southern Hemisphere Glaciers
The Bruggen (Pio XI) glacier in Chile increased in length from 1960 to 2016 and is now stable. The Perito Moreno
glacier in Argentina is also stable.
At least 58 New Zealand glaciers advanced between 1983 and 2008. CO2 content had increased from 345ppm to
385ppm but was having no warming effect. The observers noted that the glaciers advanced due to lower
atmospheric temperatures.
Observed advances in Southern Hemisphere glaciers at latitudes close to 45
o
S were contrary to the receding
behaviour of Northern Hemisphere glaciers. They agree with the observed global temperature change maps
included in Section 9 above.
13. Conclusions

1. Dr James Hansen of NASA and Sir John Houghton of the UK Meteorological Office (both fervent
environmentalists) were mistaken in their belief that increasing atmospheric CO2 content is the main cause of
climate change. In the years from 1979 to 2014, the Extent of Antarctic Sea Ice increased, even though
atmospheric CO2 content increased from 335ppm to 390 ppm worldwide. Observations of world temperatures
and glacier length showed that CO2 increase had no effect on the climate in areas south of 45
o
S. There was no
significant change to Antarctic Sea Ice Extent from 1979 to 2020/1 (with CO2 at 410ppm), both latter years being
very close to the 1981-2010 Median.
2. Atmospheric CO2 content is still less than 0.05% or 1 part in 2,000. Observations of nature show it has no
detectable effect on climate, but any increase does improve plant photosynthesis and crop yields.
3. More than 200,000 dams with greater than 15m height have been installed worldwide since year 1900, with
around 90% in the Northern Hemisphere. The UN Food and Agriculture Organisation estimated that 300 billion
tonnes of water vapour rose into the atmosphere from their associated reservoirs in 2010. The quantity of solar
energy to produce this amount of water vapour is greater than all the energy used by humans for their activities of
industry, travel and home heating/cooling. Two of the largest reservoirs are at the Aswan Dam in Egypt (Lake
Nasser) which reached full capacity in 1976, and the Three Gorges Dam in China (reservoir filled by 2010).
4. Normal atmospheric content of water vapour (known by IPCC as the most important greenhouse gas) is 1% at
60
o
latitudes and 3% in tropical areas. This is 20 to 80 times the concentration of CO2 and is boosted locally by
farmers growing crops in semi-arid and desert areas using various forms of irrigation. The World Resources
Institute estimates total freshwater withdrawals for irrigation at 3,200 billion tonnes per annum since year 2000.
The IPCC has practically ignored the enhanced water cycle over land areas caused by irrigation. Humans perspire
under hot sun and plants transpire 98% of the water absorbed by their roots.
5. There has been a large delivery of water for irrigation by pumping from underground aquifers such as the
Ogallala in the USA and in the Punjab region of India, amounting to around 40% of the total. Following distribution
in fields, the water vapour produced by evapotranspiration from crop fields eventually condenses and runs off to
raise sea level.
6. There has been a proliferation of flooded rice paddies to feed at least 4 billion people in Pakistan, India, China,
Japan and other nations in south-east Asia. The freshwater needed for flooding the fields is largely supplied from
dam reservoirs by irrigation canals and pipelines.
7. Crop irrigation causes the transfer of Latent Heat from the area of evaporation to the location of condensation.
This may explain why Alaska has recorded the largest increase in temperatures due to water vapour being
transferred by Ferrel Cell winds from irrigated crops in China.

25. True Science of Climate Change – October 2025 25 of 28
8. Hadley Cell winds transfer water vapour towards the Equator, causing increased storms which may develop into
hurricanes and tornadoes. When the vapour condenses, it releases latent heat energy and forms the larger water
droplets of torrential rain.
9. Winds in the Ferrel Cells transfer water vapour and latent heat energy poleward. Areas under the windborne
vapour (the primary greenhouse gas) retain more of their daytime heat. The Aral Sea in central Asia has almost
dried out due to upstream dams and reservoirs providing water for irrigation. Land areas North of 40
o
N
experience: a) more storms due to atmospheric warming from latent heat release, b) increased rainfall and
flooding as the vapour condenses, and c) reduced permafrost.
14. Recommendations
1. NASA should publish the truth that water vapour arising from irrigating crops with at least 3,000 billion tonnes
of freshwater every year is the major cause of climate change. UN and national government policies can then be
directed aptly, instead of wasting resources on immediate reduction of CO2 emissions.
2. Freshwater withdrawals for crop irrigation should be reduced. For example, there are foods and methods that
need much less water than flooded rice paddies.
3. World human population growth should be reduced by family planning. The UN should encourage family
planning limited to two children per family.

About the Author

Keith Shotbolt graduated from the University of Birmingham with a first in Mechanical Engineering. He then
gained 12-years-experience in general engineering before entering oil and gas field development companies. His
34 years with them included engineering and construction supervision to resist extreme storms and extreme
temperatures. He is married with 2 children and 5 grandchildren.
Questions/comments on this Study Report can be addressed to [email protected]

26. True Science of Climate Change – October 2025 26 of 28
Appendix - IPCC Reports on Atmospheric Water Vapour and associated Latent Heat.
The Intergovernmental Panel on Climate Change (IPCC) Assessment Reports AR1, AR2 and AR3 have numerous
sections on the effect of water vapour and associated latent heat, see the quotations below.
The Summaries for Policymakers (SPMs) of these Reports, and those issued later, largely ignore these observations
of increased water vapour and Northern Hemisphere precipitation.
The SPMs concentrate on the ‘radiative forcing’ of other greenhouse gases (mainly carbon dioxide) and
completely ignore the Southern Hemisphere observations described in Sections 9 to 11 above.

IPCC AR1 1990 (All IPCC Reports are freely available on the Internet)
Policymakers Summary, The Role of the Oceans section, states:
Page xxxviii (46) Water vapour, evaporated from the ocean surface, is transported by the atmospheric circulation
and provides latent heat energy to the atmosphere.
Author’s Note: it seems he IPCC did not appreciate that water vapour evaporates similarly from irrigated crops.
Chapter 1. Greenhouse Gases and Aerosols
Page 7 (55) Tropospheric water vapour is the single most important greenhouse gas, but its atmospheric
concentration is not significantly influenced by direct anthropogenic emissions (activities).
Author’s Note: The IPCC chose to ignore the effect of 2,500 billion tonnes of crop irrigation water – artificial rain -
distributed over semi-arid and desert land in the year 1990.
Chapter 7. Observed Climate Variation and Change
Page 232 (280) 7.11.3 Tropical Cyclones
Tropical cyclones derive their energy mainly from the latent heat contained in the water vapour evaporated from
the oceans.
Chapter 11. Narrowing the Uncertainties
320 (368) 11.2 3 Precipitation and Evaporation
The condensation of water is the main energy source of the atmospheric heat engine and the transport of water
vapour by the atmospheric circulation is a key process in the redistribution of the Sun’s energy in the Earth
system.

IPCC AR2 1995
Chapter 1. The Climate System: an overview
61 (page 75 of 588) 1.4.2 The Role of the Oceans
Water vapour, evaporated from the ocean surface, provides latent heat energy to the atmosphere.
Chapter 3. Observed Climate Variability and Change
161 (page 175 of 588) 3.3.7 Water Vapour
Water vapour is the most abundant greenhouse gas and makes the largest contribution to the natural greenhouse
effect.
163 (177) 3.3.9 Summary of Section 3,3.
Precipitation has increased over land in high latitudes of the Northern Hemisphere, especially during the autumn.

27. True Science of Climate Change – October 2025 27 of 28

Chapter 4. Climate Processes
200 (214) 4.2.1 Water Vapour Amounts
Since water vapour is the most important greenhouse gas, such increases in water vapour enhance the
greenhouse effect; that is, they reduce the thermal infrared (long-wave) flux leaving the atmosphere-surface
system,
Chapter 6. Projections of Future Climate
332 (346) 6.5.4 Extreme Wind Events
6.5.4.1 Mid-latitude storms
The main energy sources for mid-latitude depressions are the temperature contrast between the cold polar
regions and the warmer sub-tropical conditions, and the release of latent heat as water vapour condenses in the
warm, poleward moving, ascending air.
Chapter 7. Change in Sea Level
379 (393) Ground water (underground aquifer) depletion.
Ground water pumped at a rate in excess of recharge may add to sea level. Much of this water is used for
irrigation and a major fraction is transpired or evaporated to the atmosphere or contributes to runoff, eventually
reaching the sea.
Chapter 8. Detection of Climate Change and Attribution of Causes
437 (451) 8.5.3 Diurnal Temperature Range (DTR)
Several studies in Chapter 3 reported that, since the 1950s, minimum temperatures have increased two to three
times faster than maximum temperatures over large areas of land in the Northern Hemisphere. The result is a
reduction in DTR, especially during summer and autumn.
Author’s Note: This is a result of increased atmospheric water vapour and clouds acting with greenhouse effect to
reduce emission of infra-red radiation from the warmed earth back into space - thus reducing night-time cooling.

IPCC AR3 2001
Technical Summary
30 (page 41 of 893) It is likely that total atmospheric water vapour has increased several per cent per decade over
many regions of the Northern Hemisphere.
A pattern of overall surface and lower-tropospheric water vapour increases over the past few decades is emerging
from the most reliable data sets, although there are likely to be time-dependent biases in these data and regional
variations in the trends. Water vapour in the lower stratosphere is also likely to have increased by about 10% per
decade since the beginning of the observational record (1980).
Author’s Note: No reference to the quantity of water used for crop irrigation.
Northern Hemisphere sea-ice amounts are decreasing, but no significant trends in Antarctic sea-ice extent are
apparent.
New data indicate that there likely has been an approximately 40% decline in Arctic sea-ice thickness in late
summer to early autumn between the period of 1958 to 1976 and the mid-1990s, and a substantially smaller
decline in winter.

28. True Science of Climate Change – October 2025 28 of 28

34 (45 of 893) The decrease in the continental diurnal temperature range coincides with increases in cloud
amount, precipitation, and increases in total water vapour.
The increases in total tropospheric water vapour in the last 25 years are qualitatively consistent with increases in
tropospheric temperatures and an enhanced hydrologic cycle, resulting in more extreme and heavier precipitation
events in many areas with increasing precipitation, e.g., middle and high latitudes of the Northern Hemisphere.
Chapter 1: The Climate System: An Overview
88 (99) The most variable component of the atmosphere is water in its various phases such as vapour, cloud
droplets, and ice crystals. Water vapour is the strongest greenhouse gas. For these reasons, and because the
transition between the various phases absorbs and releases much (latent heat) energy, water vapour is central to
the climate and its variability and change.
89 (100) As an example, the atmosphere and the oceans are strongly coupled and exchange, among others, water
vapour and (latent) heat through evaporation. This is part of the hydrological cycle and leads to condensation,
cloud formation, precipitation and runoff, and supplies (latent heat) energy to weather systems.
Chapter 2: Observed Climate Variability and Change
101 (112) Over the last twenty-five years, it is likely that atmospheric water vapour has increased over the
Northern Hemisphere in many regions.
103 (114) The more reliable data sets show that it is likely that total atmospheric water vapour has increased
several per cent per decade over many regions of the Northern Hemisphere since the early 1970s. Changes over
the Southern Hemisphere cannot yet be assessed.
Note: The IPCC Reports failed to appreciate that the freshwater distributed for crop irrigation, at least 2,800 billion
tonnes in year 2001, greatly increased the water vapour flux over North America and Asia.
146 (157) 2.5.3 Water Vapour
148 (159) The longer, more reliable data sets suggest multidecadal increases in atmospheric water vapour of
several per cent per decade over regions of the Northern Hemisphere.
163 (174) The decrease in the continental diurnal temperature range since around 1950 coincides with increases
in cloud amount and, at least since the mid-1970s in the Northern Hemisphere, increases in water vapour.
164 (175) The increases in lower-tropospheric water vapour and temperature since the mid-1970s are
qualitatively consistent with an enhanced hydrological cycle. This is in turn consistent with a greater fraction of
precipitation being delivered from extreme and heavy precipitation events, primarily in areas with increasing
precipitation, e.g., mid- and high latitudes of the Northern Hemisphere.
Chapter 11: Changes in Sea Level
657 (668) 11.2.5 Surface and Ground Water Storage and Permafrost
Volumes of many of the world’s large lakes have been reduced in recent decades through increased irrigation and
other water use. Sahagian et al. (1994) and Sahagian (2000) estimate that the reduced volumes of the Caspian and
Aral Seas (and associated ground water) contribute 0.03 and 0.18 mm/year to sea level rise, on the assumption
that the extracted water reaches the world’s ocean by evapotranspiration (followed by condensation and run off).