Climate change is the ongoing, human-caused global warming of our planet. It affects everything from our food to our health.
It also changes the ecosystems of our oceans and our forests. It causes severe weather and makes our communities vulnerable to droughts, floods and other natural disasters.
Scientists say climate change is caused mainly by the release of carbon dioxide (CO2), a greenhouse gas that traps heat in the atmosphere. CO2 levels have been rising steadily for the past century, and there is strong evidence that human activities are behind this change.
The greenhouse effect can cause the entire world to warm by anywhere from a few degrees to a few degrees Fahrenheit over the course of centuries. Increasing CO2 concentrations are causing the earth to heat up faster than at any time in the last 800,000 years.
As the climate gets hotter, ice sheets and other parts of the planet are melting. This is causing sea level to rise, which is threatening coastal and island communities.
Extreme temperatures can also cause widespread wildfires, as well as historic flooding in many places around the world.
People in some countries are already suffering from more extreme weather, including a recent summer of heat waves and record rainfall in Europe. These impacts are expected to get worse in the future as temperatures rise.
The impact of climate change on human health is particularly serious. As the climate gets warmer, it can lead to more heat stress and heatstroke deaths; and higher concentrations of CO2 in the air can increase respiratory illnesses like asthma.
In addition, the spread of mosquitoes carrying diseases such as malaria and dengue can grow in areas of higher temperature. These diseases could become more common and harder to treat, as more and more people are exposed to them.
Some of the effects of climate change on our health can be subtle and hard to see. For example, an increase in the number of rainstorms can make drinking water contaminated, or cause storm damage that leads to sewage overflows and other problems.
But other effects can be more immediate and obvious, such as the loss of ice sheets, river and lake ice, and plant and animal geographic ranges. As climate changes, plants and animals may have to migrate to higher latitudes, while invasive species can move into areas that they previously could not live in.
Besides the physical impact of climate change on our environment, scientists also believe that it can have negative economic and social impacts. This includes fewer resources and less income for some people, as well as more intense extreme weather events that could slash crop yields, reduce agricultural productivity and damage infrastructure in the developing world.
Scientists agree that we must act now to limit the temperature of our planet to a level that will avoid catastrophic impacts. However, we don’t have enough time to do so. We are on track to see global temperatures rise by a full 2.8degC above pre-industrial levels, even under the most stringent emissions reduction scenarios. This will likely cause coral reefs to die off, sea ice to disappear, and millions of people to suffer from water scarcity and crop failure.