Science Library - free educational site

Climate Change basics

A controversial theory, supported by the IPCC, UN and most scientific organisations, both governmental and NGOs, concerning the cumulative impact of human activities which is causing a significant change to the composition of the atmospheric gases, with the consequence of changes to the global climate stability.

Despite the broad and growing scientific consensus that anthropogenic climate change is real and a serious threat to the human economic and environmental stability, opposition from vested interest groups, primarily fossil fuel companies, have engaged in a campaign of public misinformation, designed to continue fossil fuel government subsidies and extend the period before they are forced to change to cleaner technology.

The policy of is to present the facts, and let the scientific evidence dispel the myths which have taken hold in the public arena. These myths are:

  1. That scientists are uncertain about the reality of climate change.
  2. That the fluctuations in climate and associated extreme weather are due to solar variations, or other natural cycles, and not man-made.
  3. That the capitalist free market is the best mechanism to bring about a transition to a sustainable economy.
  4. That sustainability necessarily means zero growth.
  5. That renewable energies cannot compete economically with fossil-derived energy.

The GISS Study

There is hard evidence that average global temperatures have been rising since the advent of the Industrial Revolution (towards the end of the 18th century), when largescale combustion of fossil fuels began.

GISS 2015 report, Warmest year on record: NSA/GSFC/Scientific Visualization Studio

NASA's Goddard Institute for Space Studies (GISS) has been analysing data from a global network of meteorological stations, ships and satellites, since the 1970s, and currently holds what is possibly the most comprehensive record of Earth surface, ocean and atmospheric temperatures. Their findings are conclusive:

1. The average global temperature on Earth has increased by about 0.8°Celsius since 1880.

2. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade.

3. The 1980s was the hottest decade to date since records began (1880s). The first decade of the 21st century became the hottest decade to date, with 5 years between 1998 and 2006 the hottest years ever.

GISS images
Images courtesy of NASA’s Goddard Institute for Space Studies (GISS)

Taking the average temperature for the years 1951-80 as a baseline for comparison, GISS has prepared the above maps, which show how much deviation there is in the two decades, 1970-79 and 2000-09. All of the deviations are positive, and at an increasing rate of increase. This observation is exactly in line with the theory that greenhouse gases from human activities are responsible for the retention of heat by the Earth, the so-called 'Greenhouse Effect'.

Solar activity, aerosols, and C02 are all modelled against this data to determine the correlations. The conclusion is inevitably the same: the increase in temperature is real and is due to the changes in balance between the amount of energy the Earth receives from the Sun, and the amount it radiates back into space. The incoming radiation varies very little, but the amount of energy re-radiated has changed significantly. This change cannot be correlated to the variations in solar activity. The conclusion is that the cause is changes to the composition of the atmospheric gases.

The map (courtesy of NASA GISS, 2006) is a coloured representation of temperature anomalies. The blue and red colouring graphically represent temperature variations from the baseline reference, which is the mean between 1951 and 1980.

It can be seen that the general trend is towards unevenly distributed warming of the globe, with the polar regions receiving more than the average increase in temperature.

IPCC Reports

This data matches the models and reports released by the IPCC, the Intergovernmental Panel on Climate Change, established in 1992 by the UNO to study the science and report measurements, and make predictions about, climate change.

Involving 1,200 authors, and reviewers from 113 nations, the current prediction is for a warming of the Earth's oceans and atmosphere by at least 0.2 °C per decade. The report is unanimous that the bulk of the cause is due to human activities, primarily fossil fuel burning and deforestation.

It should be noted that in general detractors from the climate change scenario have been unable to provide any substantial scientific evidence of their own, and have relied on emphasising the uncertainties and lack of data in the IPCC reprots, and other climate change reports and studies. As time has gone on, the scientific evidence has consistently supported the conjecture of anthropogenic source of accelerated global warming, and the position of the detractors has become less and less tenable.

With climate change an accepted fact, the denialists have changed strategy to delay moves to counter the causes by debating the nebulous economic and political issues, rather than the scientific reality. The only sector which stands to gain from delaying action to curb greenhouse gas emissions is those with vested interests. In the US, these are powerful lobby groups, primarily fossil fuel energy companies.

NASA and NAS recommended further reading:

  • Hansen, J., R. Ruedy, M. Sato, and K. Lo (2010). Global surface temperature change. Reviews of Geophysics.
  • National Academy of Sciences (2010). Advancing the Science of Climate Change. Accessed December 1, 2010.
  • National Academy of Sciences (2006, July 27). Testimony to U.S. House of Representatives -- Climate Change: Evidence and Future Projections. Accessed November 30, 2010.
  • NASA (2010, January 21). 2009: Second Warmest Year on Record; End of Warmest Decade. Accessed November 30, 2010.
  • NASA (2010, January 21). NASA Climatologist Gavin Schmidt Discusses the Surface Temperature Record. Accessed November 30, 2010.
  • NASA Earth Observatory (2010, June 3) Fact Sheet: Global Warming. November 30, 2010.
  • NASA Goddard Institute for Space Studies (n.d.). GISS Surface Temperature Analysis. Accessed November 30, 2010.
  • NOAA National Climatic Data Center (n.d.). Global Warming Frequently Asked Questions. Accessed December 1, 2010.
  • NOAA Paleoclimatology. (n.d.) Climate Timeline Tool: Climate Resources for 1000 Years. Accessed December 1, 2010.
  • NOAA Satellite and Information Service (2010, July) State of the Climate in 2009. Accessed December 1, 2010.
  • NASA: 2006 Was Earth’s Fifth Warmest Year February 8, 2007.
  • IPCC Summary Report for Policymakers
  • Morton, O., and Jones, N. (2007). Climate report released: Fourth round of IPCC pins down blame for global warming. Nature. February 2, 2007. doi:10.1038/news070129-15
  • Giles, J. (2007). From words to action. Nature. 445, 578-579. February 8, 2007.

CO2 Emissions from power plants

KraftwerksartCO2 pro kWh (g)
Kernkraftwerk10 - 30
Wasserkraft10 - 40
Windenergie10 - 40
Photovoltaik50 - 100
Erdgas400 - 550
Steinkohle790 - 1080
Braunkohle980 - 1230
Deutschland Strom-Mix (2007)604

Quellen: Süddeutsche Zeitung 2007, Bundesministerium BMWI, World Nuclear Association

Gesamterzeugung aller Kraftwerke in TWh636,5610,6
Strom-Mix g pro kWh60461
Gesamt-CO2 in Milliarden kg38437
Anzahl der großen thermischen Kraftwerksblöcke7015
Anzahl der Kernkraftwerksblöcke1758

Climatologists study the Earth's past and present climate. They collect data about the Earth's past from a number of sources. There is geological evidence, and deep ice brought up as kilometer-long cores reveal much about the atmospheric gases of up to half a million years ago. They use floral and faunal records, and study the processes during and between glacial eras. Isotopes can be found in sediments, and these reveal a variety of facts about past sea levels and solar radiation.

Icemelt between 1989 and 2011, Bear Glacier, Alaska

The number of variables involved in the climate is truly awe-inspiring. Computers are a vital tool in developing models to try to understand the complexities. As these models are created, new data can test their accuracy, and they can be adjusted over time to give ever preciser models. This is the area of computational science, in which computers can teach themselves about the models, and to some extent develop them independently of human 'tweaking', which could be biased or too focussed on certain issues.


IPCC stands for the United Nations appointed InterGovernmental Panel on Climate Change. The panel was established in 1988 by the WMO (World Meteorological Organization) and UNEP (United Nations Environment Programme), and has the mandate to collect scientific data concerning anthropological climate change, and make reccomendations based on its findings. It has released 5 reports:

  1. IPCC First Assessment Report, 1990
  2. IPCC Second Assessment Report, 1995
  3. IPCC Third Assessment Report, 2001
  4. IPCC Fourth Assessment Report, 2007
  5. IPCC Fifth Assessment Report, 2014

These reports support the UNFCCC (United Nations Framework Convention on Climate Change), the principal treaty for coordinating international response to the threat of climate change. The aim of the UNFCCC is: "to stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic [i.e., human-induced] interference with the climate system".

To support this aim, the IPCC investigates the "the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation." It does this by collating findings from a broad range of scientific publications, from thousands of scientifically-qualified authors. It upholds the peer-reviewed requisite for sources.

The IPCC reports also contain a "Summary for Policymakers", involving the approval of more than 120 governments.

In recognition of the outstanding quality of work, and its vital importance, in the face of fossil fuel industry anti-propaganda tactics and American vested interest obstruction and denial, the IPCC was awarded the 2007 Nobel Peace Prize, shared with Al Gore, also a high-profile climate change activist. The award of the Peace Prize was also an acknowledgement that destabilising climate is a major cause of human socio-economic distress, deprivation, displacement, and political breakdown and consequent war.

The Kyoto Protocol is a 1997 agreement, which is part of the 1992 UNFCCC, United Nations Framework Convention on Climate Change, 1992.

A protocol is a supplemental treaty or agreement to an initial treaty. The UNFCCC (United Nations Framework Convention on Climate Change, 1992) set out a general framework for greenhouse gas emission reductions. More specific individual targets, provisions and regulations, were nutted out and set down in the Kyoto Protocol, 1997. Playing its part as perennial obstruction to international consensus, the USA demonstrated the principle that signing the original treaty does not oblige a state to sign and ratify the subsequent protocols, thereby undermining the will and spirit of the other 192 states who did sign and ratify both the treaty and subsequent protocol.

sea rise Europe
Europe with 80m sea rise

One of the most-known predictions by the IPCC is the potential rise in sea level with rise in global average temperature. The most recent report puts the expected rise in global temperature by 2050 at between 2 and 3°C relative to the start of the Industrial Revolution (when fossil fuels were started to be used en masse). The prediction is for a 59cm rise in sea level.

The precision of the prediction belies the fact that there is a great deal of uncertainty involved. This is due to unknowns such as the rate of ice melt. Jim Hansen, of NASA/GISS, has a far more dramatic expectation: a sea level rise of 25m at 3°C temperature increase, and in a much shorter timeframe. This estimate is based on studies of ice melt in the polar regions, which may not occur linearly with temperature rise, but 'flip' states, suddenly changing from solid ice to water, and causing considerable sea level rise in short time.

2% of global water is ice and snow, so if this enters the oceans, and the average sea depth is 3800m, a rise of 76m is anticipated, In addition, since the oceans are warmer, there will be an expansion of the volume of the sea, bringing the rise to over 80m. Since the majority of large human cities are situated on coasts, a sea rise of this magnitude would be devastating to human civilisation, no matter how protracted the occurrence.

IPCC Report

"Vested interests are paying for the discrediting of scientists all the time. We need to be ready for that." Halldór Thorgeirsson, UN official (IPCC AR5).

The United Nations Intergovernmental Panel on Climate Change (IPCC) was established in 1988, following the 1986 Brundtland Report recommendations. Its task is to collate information from a vast group of contributors, mainly scientists, concerning the verification and consequences of global warming, and the consequent climate change.

Despite the almost unanimous support of the findings by the scientific community around the world, policy-makers have failed to act in a way which would seem logical, given the seriousness of the consequences of climate change. This failure has been due to interest groups, mainly fossil fuel companies and similar vested interests, who wish to obfuscate public perceptions, with the intent of delaying any meaningful political action.

One of the parameters commonly requested by the lay public is an estimate of expected sea level rise - a factor seen to have immediate impact on human civilisation. However, there are so many variables involved, it has taken a long time to develop models which may be considered to have any reliability. There remains a broad uncertainty as to how much sea levels may rise. It is unlikely to be linear - a set number of metres per degree of temperature rise - since the rise is due to two chief factors: calorific expansion and the liberation of liquid water from permanent or long-term stores of ice, snow, and permafrost.

The IPCC Fifth Assessment Report (AR5) was published in 2014. One of its summary statements:

  • Warming of the atmosphere and ocean system is unequivocal. Many of the associated impacts such as sea level change (among other metrics) have occurred since 1950 at rates unprecedented in the historical record."
  • It is likely (with medium confidence) that 1983—2013 was the warmest 30-year period for 1400 years.
  • It is virtually certain the upper ocean warmed from 1971 to 2010. This ocean warming accounts, with high confidence, for 90% of the energy accumulation between 1971 and 2010.
  • It can be said with high confidence that the Greenland and Antarctic ice sheets have been losing mass in the last two decades and that Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.
  • There is high confidence that the sea level rise since the middle of the 19th century has been larger than the mean sea level rise of the prior two millennia.

IPCC 2014 Projections

  • Further warming will continue if emissions of greenhouse gases continue.
  • The global surface temperature increase by the end of the 21st century is likely to exceed 1.5 °C relative to the 1850 to 1900 period for most scenarios, and is likely to exceed 2.0 °C for many scenarios.
  • The global water cycle will change, with increases in disparity between wet and dry regions, as well as wet and dry seasons, with some regional exceptions.
  • The oceans will continue to warm, with heat extending to the deep ocean, affecting circulation patterns.
  • Decreases are very likely in Arctic sea ice cover, Northern Hemisphere spring snow cover, and global glacier volume.
  • Global mean sea level will continue to rise at a rate very likely to exceed the rate of the past four decades.
  • Changes in climate will cause an increase in the rate of CO2 production. Increased uptake by the oceans will increase the acidification of the oceans.
  • Future surface temperatures will be largely determined by cumulative CO2, which means climate change will continue even if CO2 emissions are stopped.

Further Summary Statements:

- The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.

- Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.

In other words, the world will experience climate change, even if human damage to the biosphere were to cease immediately.

Content © All rights reserved. Created : April 29, 2015 Last updated :June 9, 2016

Latest Item on Science Library:

The most recent article is:


View this item in the topic:

Vectors and Trigonometry

and many more articles in the subject:

Subject of the Week


Information Technology, Computer Science, website design, database management, robotics, new technology, internet and much more. JavaScript, PHP, HTML, CSS, Python, ... Have fun while learning to make your own websites with

Computer Science

Great Scientists

Julius von Sachs

1832 - 1897

Julius von Sachs was a German botanist who was a pioneer of plant physiology.

Julius von Sachs

Quote of the day...

Do unto future generations as we hope previous generations did unto us.

ZumGuy Internet Promotions

Transalpine traduzioni