The science and impacts of climate change

Scientists have developed an understanding of the earth’s climate system through years of observations. We now know that global warming is the result of greenhouse gas emissions caused by human activity.

Since the late 19th century, the global average temperature has risen by about 1°C and the global sea level has risen by about 20cm. The rising temperature is leading to wider changes to our weather. At the same time, increased CO2 levels are causing the world’s oceans to become more acidic.

Many impacts of climate change are already being detected, including:

  • warming of the troposphere (the lower part of the atmosphere)
  • acidification of the oceans
  • rising sea levels
  • declining glaciers and sea ice
  • slowing of increases to crop productivity

There is no clear threshold where climate change moves from safe to dangerous. We can expect some disruptions and irreversible losses of natural habitats and resources, even with a 2°C temperature rise.

However, with rapid global action to cut greenhouse gas emissions, we can still reduce the likelihood of global temperatures increasing by 2°C. On the other hand, if we take no action, global temperatures could increase by 7°C or more.

That is why it is sensible to take action now to insure against the risks of dangerous climate change.

Read the latest evidence about how and why our global climate is changing from some of the world’s leading science organisations: