5 FACTS TO KNOW

There are at least five lines of scientific evidence showing the Earth’s climate is changing:

1 Paleoclimate

Earth’s climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat. The last ice age, about 11,700 years ago, had an abrupt end.

2 Atmospheric CO2

The heat-trapping properties of carbon dioxide (CO2) — and other gases like methane — in the atmosphere was demonstrated in the late 1930s. In 1938, British scientist Guy Callendar linked CO2 increases in Earth’s atmosphere to global warming.

3 Rising temperature

The planet’s average surface temperature has risen about 2.12 degrees Fahrenheit (1.18 degrees Celsius) since the late 19th century.

4 Warming Ocean

The ocean has absorbed much of this increased heat, with the top 100 metres (about 328 feet) of ocean showing warming of more than 0.6 degrees Fahrenheit (0.33 degrees Celsius) since 1969, according to a NOAA data set.

5 Shrinking Ice Sheets

The earth’s ice caps are shrinking, and fast. Scientists say the main reason is a warming ocean under the ice. A new survey of satellite data shows that Greenland and Antarctic ice sheets have significantly decreased in mass over the past few decades.