Evidence

‘When one tugs at a single thing in nature, he finds it attached to the rest of the world.’ John Muir, Scottish naturalist and writer, 1838-1914

Global average temperatures rose by around 0.7˚C over the 20th century and 1998 was the warmest year since records began in 1861, with 2005 almost as warm.

Evidence of global warming has been found in ice cores from Greenland and Antarctica, and in changes to nature’s calendar already seen in Scotland. Spring plants are blooming earlier in Scotland (on average three weeks earlier since 1978) and migrating birds are arriving earlier.

All of the evidence points to the primary cause of this warming being an increase in concentrations of greenhouse gases in the Earth’s atmosphere, as a result of human activities since the industrial revolution. Concentrations of carbon dioxide (CO₂) in the atmosphere have risen by more than 30% since the industrial revolution and are now rising faster than ever before. Greenhouse gas emissions are driving climate change.

Climate scientists are studying the ice in Greenland and Antarctica as they have both shown important melting over the last 50 years. Around the world, glaciers are retreating and disappearing in line with warming trends in global and local temperature.

In recent years every summer has seen less and less Arctic sea ice. Scientists predict that there may be no Arctic sea ice in summer months by 2040.

Visit the National Snow and Ice Data Center at the University of Colorado at Boulder to find out more about reducing levels of sea ice and to get a daily update on sea ice coverage.