Measuring a warming world

Scientists are continually monitoring trends in climate, such as temperature, sea level, ocean heat, snow and ice. Often several different research groups monitor the same issues, using different evaluation methods. Any consensus reached gives added confidence in those trends.

Climate change is most commonly measured using the average surface temperature of the planet. Current records from the UK Met Office, NASA and the US National Climatic Data Centre show global temperature at roughly 0.8°C above 1900 levels. Natural, year-on-year, fluctuations can be seen on top of this long-term warming. For this reason scientists traditionally use a period of at least 30 years to identify a genuine climate trend.

Carbon budget exhibits_1

Other indicators  also confirm that the world is warming. For instance, sea level is rising, ocean heat content is increasing, glaciers & sea ice are declining, and the troposphere (the lowermost 10 kilometres or so of the atmosphere) is warming.

Temperature in the last few years – has global warming stopped?
Records of global average surface temperature show that the rate of increase observed in the second half of the 20th Century has not been maintained in the last few years. Many people have therefore asked if global warming is over.

It is important to remember that trends in climate need to be considered over significant periods – typically 30 years. Over shorter periods natural fluctuations can mask (or add to) those longer-term trends. Looking at global temperature records since the 1980s and before, the long-term increase is clearly in evidence. And the short-term slowdown is not seen in other climate indicators such as glacier mass, sea ice extent and sea level.

Based on our knowledge of the physics of the greenhouse effect and global emissions, we can expect temperatures to continue to rise over the long-term.

Further information can be found in our one-page “pause” briefing.