Climate Change – The data

Page revised September 2017.

About this page

This page shows some of the data used to see how climate is changing. It may help understanding of both the problem and the problems of understanding this complex issue. There are some comments about the data but none on conclusions that might be drawn about why climate is changing.

How do we know the climate is changing?

There are many problems with the data and, not surprisingly, much distrust of data analyses. There are several data sources and they all point in one direction. It is getting warmer.


Measurements of surface temperature.

There are no long-term records of temperature with no changes of instrument, site location, local land use or observing procedure. Consequently, there is no definitive data set of global temperatures.

There are a few composite data sets for specific locations or areas; the best known is the Central England Temperature (CET) series started by Professor Manley and maintained by the Met Office Hadley Centre. See http://hadobs.metoffice.gov.uk/hadcet/.

Globally, there are several “best efforts” produced by various groups working independently. Notably, these are the NASA Goddard Institute Space Studies (GISS), the NOAA National Climate Data Center (NCDC), the UK Hadley Centre and the University of East Anglia Climate Research Unit (HadCRU), the Japanese Meteorological Agency (JMA) and the Berkley Earth (BEST.)

The last, Berkeley Earth was conceived by Richard and Elizabeth Muller of the University of California at Berkley in early 2010 when they found merit in some of the concerns of climate sceptics.

The results of the first three and last group are summarised here –

and

The latest JMA series can be found at https://ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/ann_wld.html. This site shows monthly and annual series. It is continually updated.

This was produced in 2017.


Sea Surface temperatures.

The oceans contain roughly 90% of the total heat in the system, the atmosphere has about 3%. Thus, sea temperatures should be a better guide to what is happening globally.

As with land records sea temperature data although not affected by land use have other problems. Initially, in the late 19th century, sea temperatures were measured by dropping a bucket into the sea, pulling it out and measuring its temperature. During and after WW2 there was a transition to using the temperature of water at the engine se water intake. Then, later, satellites have been used to measure the radiation, therefore the temperature, from the sea surface. Also we now have a wealth of data from tethered and drifting data buoys. Each technique has different characteristics and much effort has gone into fata interpretation and homogenisation.


Ocean heat content

The volume of water in the oceans is a good measure of total heat in the system. Sea levels have risen for two reasons, thermal expansion and melting of ice. There are tidal gauge data dating back to the mid 19th century, few initially but increasing over time. More recently there are satellite measurements.

In recent years ocean heat content has been estimated from data obtained at various depths. This is an example from the US EPA site, https://www.epa.gov/climate-indicators/climate-change-indicators-ocean-heat .


Other data.

Micro-wave instruments on satellites provide a measure of the temperature of the lower atmosphere. See http://www.drroyspencer.com/latest-global-temperatures/. As with conventional instrumental data there are problems in data analysis, this time due to changes of instrument and drift in calibration. Acter 38 years of data the program is now Ver 6.

A totally different approach is that used by the European Centre for Medium Range Weather Forecasting (ECMWF). They analyse weather in 4 dimensions for their routine forecasts. All types of data are used in their analyses. These cover the whole of the atmosphere up to about 80 km. From these analyses, they extract surface temperature over the whole of the globe. See https://climate.copernicus.eu/news-and-media/press-room/press-releases/earth-edge-record-breaking-2016-was-close-15%C2%B0c-warming. This is the version as at September 2017 –


CO2 in the atmosphere.

This is fundamental to climate change understanding. These are of fundamental importance if global climate change is a result of using fossil fuels.

Monthly mean atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii

The annual mean carbon dioxide growth rates for Mauna Loa. In the graph, also decadal averages of the growth rate are plotted, as horizontal lines for 1960 through 1969, 1970 through 1979, and so on.
This shows CO2 levels during the last three glacial cycles, as reconstructed from ice cores. (Source: https://climate.nasa.gov/vital-signs/carbon-dioxide/)


Palaeolithic data

There are a multitude of data sources using ice cores, carbon dating, tree rings etc. The derived data can only be very general.

This shows 1000 years of data. The upper diagram is one produced by Professor Michael Mann who used the now much derided description of “hockey stick.” The lower diagram is a collection of analyses from a variety of sources.

This is a longer term reconstruction of global temperature and CO2 from https://www.ncdc.noaa.gov/global-warming/temperature-change.

These are CO2 amounts over the past 1000 years.

The following is a reconstruction of CO2 concentrations showing values over the past 400,000 years compared to present values – now over 400 ppm.

From https://climate.nasa.gov/vital-signs/carbon-dioxide/

These are reconstructions of sea level over the past 2000 years.

From https://www.cmar.csiro.au/sealevel/sl_hist_few_hundred.html


Polar ice – the Arctic

The Arctic is an area of sea surrounded by land. This diagram shows how the extent of Arctic sea ice has decreased over recent years.

The graph above shows Arctic sea ice extent as of March 20, 2017, along with daily ice extent data for five previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, 2012 to 2013 in purple, and 2011 to 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index (Source - http://nsidc.org/arcticseaicenews/)

Greenland's ice lost is a major concern.

Melt streams on the Greenland Ice Sheet on July 19, 2015. Ice loss from the Greenland and Antarctic Ice Sheets as well as alpine glaciers has accelerated in recent decades. NASA photo by Maria-José Viñas

(Source: - https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level)


Antarctic land ice amount

The Antarctic is a land mass surrounded by sea. It behave differently to the Arctic. The melting of the land ice over the Antarctic continent is a measure of warming of that area.

Paradoxically, the melting of the land ice has led to an increase in the area of sea ice. However, the volume of sea ice gain is substantially less than the loss of land ice.

''The continent of Antarctica has been losing more than 100 cubic kilometers (24 cubic miles) of ice per year since 2002.

See the Antarctic Sea Ice Index''

(source - http://www.nasa.gov/topics/earth/features/20100108_Is_Antarctica_Melting.html)


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