The Earth’s climate has been in constantly changing since the beginning of time. It will continue to change in the future. The temperature of the Earth has fluctuated (increased and decreased) over the last few hundred years. Since 1950, however, there has been a significant increase in global temperatures that is attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels. This is commonly known as climate change.
Evidence of climate change
Temperature records from the use of thermometers have shown an increase in the Earth’s temperature. Using the data scientists have recorded an increase in the average combined land and ocean surface temperature. An increase of 0.85°C since the end of the 19th Century.
The 20 warmest years on record have been in the past 22 years, with 2015-2018 making up the top four, the WMO says.
If this trend continues, temperatures may rise by 3-5C by 2100.
The graph below shows changes in the global average (land and sea) temperature anomaly between 1948 and 2017.
Future temperature increases will depend on natural changes in climate and the volume of greenhouse gases being released into the atmosphere. Average global temperatures will continue to rise if greenhouse emissions continue at their current rate. Though some regions, such as the Arctic, will warm at a faster rate than others.
Photographs of glaciers taken years apart show that many of the world’s glaciers are melting and in retreat. As well as melting valley glaciers ice sheets are also in retreat at the Arctic. The increase in global temperatures is causing widespread melting of ice.
The time-lapse video below shows the retreat of Chile’s Jorge Montt Glacier between 2010 and 2011. The video shows the withdrawal of nearly a mile in a year.
Ice cores are used by scientists to identify changes in temperature. Falling snow traps air into the ice. When ice cores are taken changes in the atmospheric concentration of gases when the snow fell are revealed. This data can be used to calculate the temperatures at the time. Ice cores can be used to identify the temperature of every year for the last 400,000 years. Ice core studies identify clear evidence of a rapid increase in temperature over the last few decades.
The image below shows scientists drilling for ice cores.
There is evidence of season shift over recent years. With spring arriving earlier and winters being less severe. This can have a negative impact on nesting and migration patterns of birds and mammals.
Rising sea levels
Average global sea levels have risen by 0.19m between 1901 and 2010.
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