Why is the Earth warming?
Global warming is the slow increase in the average temperature of the earth’s atmosphere. More and more of the sun’s energy is being trapped in the atmosphere and not radiated out into space.
This is happening because human activities are increasing the concentration of CO2 and other greenhouse gases, such as methane, and nitrous oxide, plus some chemically manufactured greenhouse gases such as halocarbons.
These human-generated gases enhance the natural greenhouse effect and further warm the surface.
Observed changes in our climate system
The global warming of the past 50 years is primarily due to human activities.
Many of the impacts of climate change pose risks to human and natural systems, in the form of more frequent and severe heat waves, coastal inundation due to sea level rise, disruptions to rainfall patterns and other effects. Analyses of a range of climate scenarios indicate the most severe risks of climate change can largely be mitigated if carbon dioxide emissions are reduced to the point where carbon dioxide is no longer accumulating in the atmosphere.
Global climate is changing, and this change is apparent across a wide range of observations.
INCREASING AIR TEMPERATURES
Air temperatures have increased globally by around 1.1 degrees Celsius since the late 1800s. Most of the warming from 1880 to present has occurred since the 1970s. The years 2015 and 2017 were the equal second warmest years on record globally.
Rainfall patterns are changing around the world. Research shows the global water cycle is intensifying with a warming climate, which means wet areas are likely to get wetter and dry regions are likely to be drier, responding to climate change.
OCEAN WARMING AND SEAL LEVEL RISE
EXTREME WEATHER EVENTS
Extreme weather events include heatwaves, bushfires, tropical cyclones, cold snaps, extreme rainfall including flash flooding, and droughts. These events have serious impacts on our economy, society, and environment.