Climate: Long range Investigation, Mapping, and Prediction, known as CLIMAP, was a major research project of the 1970s and 80s to produce a map of

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologica ...

conditions during the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eu ...

. The project was funded by the

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

as part of the International Decade of Ocean Exploration (1970s) and is based in large part of the collection and analysis of a very large number of sediment cores to create a snapshot of conditions across the

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

s. The CLIMAP project also resulted in maps of vegetative zones across the continents and the estimated extent of glaciation at the time. Most CLIMAP results aim to describe the Earth as it was 18 thousand years ago, but there was also an analysis to look at conditions during the previous

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene ...

—120 thousand years ago (CLIMAP 1981). CLIMAP has been a cornerstone of

paleoclimate Paleoclimatology ( British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important t ...

research and remains the most used sea surface temperature reconstruction of the global ocean during the last glacial maximum (Yin and Battisti 2001), but it has also been persistently controversial. CLIMAP resulted in estimates of global cooling of only 3.0 ± 0.6 °C relative to the modern day (Hoffert and Covey 1992). The

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

during an

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

that occurs far from the continental

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at ...

s themselves is believed to be primarily controlled by changes in

greenhouse gas A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), met ...

es, hence the conditions during the last glacial maximum provide a natural experiment for measuring the impact of changes in greenhouse gases on climate. The cited estimates of 3.0 °C implies a climate sensitivity to

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

changes at the low end of the range proposed by the

Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) a ...

.
However, CLIMAP also suggested that some of the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred ...

and in particular much of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

were warmer than they are today. To date, no

climate model Numerical climate models use quantitative methods to simulate the interactions of the important drivers of climate, including atmosphere, oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the ...

has been able to reproduce the proposed warming in the Pacific (Yin and Battisti 2001), with most preferring a several degree cooling. Also, it appears that climate models which are forced to match the CLIMAP sea surface measurements are too warm to match estimates for changes at continental locations (Pinot ''et al.'' 1999). This suggests that either climate model design is missing some important unknown factor, or CLIMAP systematically overestimated the temperatures in the tropical oceans during the last glacial, though there is at present no consistent explanation for why or how this should have happened. Unfortunately cost and difficulty of collecting sediment cores from the open Pacific has limited the availability of samples that might help to confirm or disprove these observations. If the Pacific reconstruction is assumed to be in error, it would result in a larger climate sensitivity to changes in greenhouse gases.

References

* * * * *CLIMAP Data Archive. https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ngdc.mgg.geology:G00126

External links

PMIP Home pagePMIP2 Home pageMOTIF Home page
{{Global warming Climatological research Paleoclimatology