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Current Climate Change

Global Warming and Rising CO2

Global average surface temperatures have increased markedly over the last century (Figure 1). Humans have been measuring temperature directly since the mid- 1800’s; these measurements show that temperature increased by 1.53°F (0.85°C ) between 1880 and 2012, and that the rate of warming is increasing (IPCC 2013 Ch. 2). With the exception of 1998, the 10 warmest years in the 134-year record all have occurred since 2000, with 2010 and 2005 ranking as the warmest years on record (NASA GIS 2014).  Although 1.53°F may not seem like a large temperature change, on a global scale this has huge implications for many of the earth’s processes that affect ecosystems and humans. To put the number in perspective, many scientists think that temperature increases in excess of 3.6°F (2.0°C) relative to 1980-1999 will create outcomes dangerous to human civilization; others say that even lesser increases would be enough to do this (Anderson & Bows 2011).

Figure showing average global temperature trends from 1880 to present.

Excess greenhouse gases in the atmosphere are a measureable and significant contributor to global warming, and their concentrations have steadily increased over the past century (IPCC 2013 Ch. 2). Carbon dioxide (CO2), the most important greenhouse gas in terms of climate change, has been measured directly since 1958. Additionally, atmospheric levels of CO2 can be reconstructed for hundreds of thousands of years into the past using methods such as analyzing air bubbles trapped in ice. CO2 concentration in late 2013 was at 395 parts per million, a level that is higher than at any point during the past 800,000 years (Global Carbon Budget 2014; Figure 2). Growth rates of atmospheric CO2are still high; CO2 emissions from fossil fuel burning and cement production  in 2013 were the highest in any other year of human history, 61% higher than CO2 emissions in 1990 (Global Carbon Budget 2014).

Figure 1 - Global temperature trend from 1880 to present, compared to a base period of 1951-1980. Global temperatures continue to rise, with the decade from 2000 to 2009 as the warmest on record Data from NASA's Goddard Institute for Space Studies (GISS).

Figure 2 - Human society is entering uncharted territory as atmospheric levels of greenhouse gases continue to rise. Today’s carbon dioxide levels are substantially higher than anything that has occurred for more than 800,000 years (last 400,000 years pictured here). Data from NOAA National Climatic Data Center and the Mauna Loa observatory.
Figure showing atmospheric carbon dioxide levels over time.

Climate Change

For an animated look at how CO2 concentrations have changed over the last 800,000 years, see this video created by the NOAA Earth System Research Laboratory

Rising global temperatures are causing the Earth’s climate patterns to change. Climate can be defined as the "average weather," or the average long-term (multi-decadal) meteorological conditions and patterns for a given area. Changes in climate that are occurring as the planet warms include seasonal and regional changes in temperature and precipitation, (USGCRP 2014 Ch. 2, IPCC 2013 Ch.2), and increasing extreme weather events (IPCC 2011). As an example, precipitation from 1991 to 2012 increased significantly in some parts of the United States including the Great Plains, Northeast, and Midwest, , and declined in other regions during the same time period, particularly parts of the Southwest and Southeast (USGCRP 2014 Ch. 2).

In conjunction with temperature and precipitation changes, during the 20th and early 21st centuries there has been a nearly worldwide reduction in glacial mass and extent, a decrease in snow cover in many Northern Hemisphere regions, a decrease in Arctic sea ice thickness and extent, a decrease in the length of river and lake ice seasons, permafrost warming, warmer ocean temperatures, and rising sea levels (IPCC 2013 Summary for policymakers), among other observed changes (Figure 3).

Figure showing changes in sea level since the late 1800's
Figure demonstrating changes in sea ice mass since 2000

Figure 3 - Multiple observed indicators of a changing climate: a. Observed sea level changes, derived from coastal tide gauge data, and b. Satellite data showing loss of ice sheet mass in Antarctica. The continent of Antarctica has been losing about 147 billion tons of ice per year since 2003. Source: NASA Global Climate Change – Vital Signs of the Planet, with original data from CSIRO and NASA.

For up-to-date information on temperature, carbon dioxide, and other indicators of a warming planet, see the NASA Global Climate Change - Key Indicators page.

Need more information?

See the following primers and resources for more introductory information on climate change.

Climate Change Resource Center: 

United States Global Change Research Program:
The Third National Climate Assessment

NASA Global Climate Change
Climate change: How do we know?

Center for Climate and Energy Solutions:
Climate Change – The Basics

Cooperative Institute for Research in Environmental Sciences:
Reading the IPCC Report - Recorded seminar series

Anderson A.; Bows, A. 2011. Beyond 'dangerous' climate change: emission scenarios for a new world. Philosophical Transactions of the Royal Society. 369: 20-44.

Bond, G.; Kromer, B.; Beer, J.; Muscheler, R.; Evans, M.; Showers, W.; Hoffmann, S.; Lotti-Bond, R.; Hajdas, I.; Bonani, G. 2001. Persistent solar influence on North Atlantic climate during the Holocene. Science. 294: 2130-2136.

Carbon Dioxide Information Analysis Center (CDIAC). 2014. Recent Greenhouse Gas Concentrations. (Accessed 10-31-2014)

Deser, C.; Alexander, M.A.; Xie, S.P.; Phillips, A.S. 2010. Sea Surface Temperature Variability: Patterns and Mechanisms. Annual Review of Marine Science. 2: 115-143.

Global Carbon Project. 2014. Carbon budget and trends 2014. (Accessed 10-20-2014)

Hansen, J.E. 2003. Can we defuse the global warming time bomb? (Accessed 10-31-2014)

Held, I.M.; Soden, B.J. 2000. Water vapor feedback and global warming. Annual Review of Energy and the Environment. 25:441-475.

Huber, M.; Knutti, R. 2011. Anthropogenic and natural warming inferred from changes in Earth's energy balance. Nature Geoscience. Advance Online Publication.

IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Averyt, K.B.; Tignor, M.; Miller, H.L. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

IPCC, 2011: Summary for Policymakers. In: Intergovernmental Panel on Climate Change, Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C. B.; Barros, V.; Stocker, T.F.; Qin, D.; Dokken, D.; Ebi, K.L.; Mastrandrea, M. D.; Mach, K. J.; Plattner, G.K.; Allen, S.; Tignor, M.; Midgley, P. M. (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA.

IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 

Lean, J. 2010. Cycles and trends in solar irradiance and climate. Wiley Interdisciplinary Reviews: Climate Change. 1: 111-122.

Li, J.;  Xie, S.-P.;  Cook, E.R.; Morales, M.; Christie, D.; Johnson, N.; Chen, F.;  D'Arrigo, R.; Fowler, A.; Gou, X.; Fang, K. 2013.El Niño modulations over the past seven centuriesNature Climate Change. 3:822-826.

Mann, M.E.; Zhang, Z.; Rutherford, S.; Bradley, R.S.; Hughes, M.K.; Shindell, D.; Ammann, C.; Faluvegi, G.; Ni, F. 2009.Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly. Science. 27 (326): 1256-1260.

Mantua, N. J.; Hare, S. R.; Zhang, Y.; Wallace, J. M.; Francis, R.C. 1997. A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the American Meteorological Society 78:1069-1079.

NASA Global Climate Change. 2014. Vital Signs of the Planet. (Accessed 10-31-2014).

NASA Goddard Institute for Space Studies. 2014. NASA Finds 2013 Sustained Long-Term Climate Warming Trend. Research News. (Accessed 10-31-2014).

NASA Earth Observatory. 2000. Features: Milutin Milankovitch. (Accessed 10-31-2014).

NASA Earth Observatory. 2009. Features: El Nino, La Nina, and Rainfall. (Accessed 10-31-2014).

NOAA Earth System Research Laboratory. 2014. Mauna Loa Observatory. (Accessed 10-31-2014)

NOAA National Climatic Data Center. 2014. (Accessed 10-31-2014).

Ramanathan, V.; Feng, Y. 2009. Air pollution, greenhouse gases and climate change: Global and regional perspectives. Atmospheric Environment. 43: 37-50.

Tyndal J. 1861. On the absorption and radiation of heat by gases and vapours, and on the physical connexion of radiation, absorption, and conduction. Philosophical Magazine. 22:169-94, 273-85

United States Global Change Research Program (USGCRP). 2009. Global Climate Change Impacts in the United States. Karl, T.R.; Melillo, J.M.; Peterson, T.C. (eds). Cambridge University Press.

U.S. Global Change Research Program2014The Third National Climate Assessment. Melillo, J.M.; Richmond, T.C.; Yohe, G.W. (eds.). 841 p.

Wanner, H.; Beer, J.; Butikofer, J.; Crowley, T.J.; Cubasch, U.; Fluckiger, J.; Goosse, H.; Grosjean, M.; Joos, F.; Kaplan, J.O.; Kuttel,M.; Muller, S.A.; Prentice, C.; Solomina, O.; Stocker, T.F.; Tarasov, P.; Wagner,M.; Widmann, M. 2008. Mid- to Late Holocene climate change: an overview. Quaternary Science Reviews. 27: 1791-1828.

Wolff, E.W. 2011. Greenhouse gases in the Earth system: a palaeoclimate perspective. Philosophical Transactions of the Royal Society. 369: 2133-2147.

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