What is global warming?

Here's Global Warming Explained...

The sun provides us with the energy that we need to sustain life. Particles in our atmosphere, called greenhouse gases, absorb heat from the sun and re-radiate it within the earth’s atmosphere. This process is called the ‘greenhouse effect and traps just the right amount of heat from the sun to allow life to thrive. Without this clever system, our planet would be about 33C colder!


When more greenhouse gases, such as carbon dioxide (CO2) and methane (CH4), are added to our atmosphere, it causes more heat to get trapped and therefore the planet to get hotter. We call this process global warming and it can have huge implications for the carefully balanced conditions which support all life on earth. Global warming is currently happening faster than it has for 65 million years


Why is the planet warming faster than it should be?

To cut a long story short - we are experiencing such speedy global warming because humans have been burning tonnes and tonnes of fossil fuels.

Over millions of years, since the mass extinction of the dinosaurs, excess carbon from decomposing plants and animals has been compressed by heat and pressure into the form of gas, oil and coal - or fossil fuels. Unfortunately, we have found these carbon reserves and decided to yank them up and burn them, thus re-releasing the greenhouse gases into our atmosphere.

For the past 10,000 years, both the amount of greenhouse gases in the atmosphere, and the temperature of our planet, have remained pretty constant. However, since the industrial revolution, when we started firing up the coal engines, the concentration of CO2 in our atmosphere has increased by 40%, making it the highest it’s been for 2.5 million years.

This sudden spike in CO2 has also led to a spike in global temperatures. Eighteen of the nineteen warmest years ever recorded have happened since 2001 and we have seen an overall increase in temperature of about 1C. This may not seem like much, but seemingly small changes to the complex, integrated systems which regulate the earth’s climate can have huge effects. It only took global warming of 5C to wipe out nearly all species on Earth 50 million years ago. Seeing as we don’t want to get to anywhere near this level of destruction, 1C of warming doesn’t seem so small.


What do these changes in temperature mean for society?

Climate change in terms of global warming can be quite deceptive. An increase in temperature of 1C doesn't mean that everywhere is a bit warmer, but that we see extremes in temperatures in different parts of the world. This creates havoc for our weather systems by messing with ocean and wind currents, providing more energy for storms and means extra intense heating for areas already vulnerable to fatally hot weather. Global warming therefore means both more severe and more frequent extreme weather events.

We are already seeing these changes. An analysis has found that of all cases of extreme weather studied over the past 20 years, 68% were made more likely or more severe because of human-caused climate change. Events like Hurricane Sandy and California’s wildfires will occur more often and with worse consequences. We can also expect much longer droughts and water shortages, impacting food security for millions of vulnerable people.

Rising temperatures don’t just make us hot, they make our oceans hot too. Our planet is 70% water and when water gets warmer, it gets bigger which causes sea levels to rise. Melting sea and land ice are also contributing to this problem.

Land loss from our swelling oceans is one of the biggest threats that climate change poses and it is already affecting communities around the world. Bangladesh, for example, is particularly exposed to rising sea levels. They are currently losing land bigger than the size of Manhattan each year and in the past ten years, an estimated 700,000 Bangladeshis have been displaced due to the effects of climate change.

It has been estimated that by 2050 we could see at least 200 million people displaced by climate change worldwide - that’s 1 in every 45 people who have had to leave their homes because of climate related issues. Climate change puts us all in danger. To prevent its most serious impacts, we need to stop our planet from getting much hotter.


How much warming is too much warming?

There is a lot of talk about keeping below 2C of warming. However, according to a special report published by the IPCC, staying below 1.5C could prevent a load of damage. For example, at 1.5C, 30% of our coral reefs may still be alive, however they are likely to have totally disappeared once we reach 2C. Coral reefs aren’t just a spectacle for the eyes, it’s estimated that 500 million people worldwide rely upon coral reefs for their livelihood. Many of these people are from poor and highly vulnerable communities.

Surpassing 1.5C of warming could also mean that we reach a tipping point when global warming will cycle up and out of control completely due to feedbacks and thresholds in the Earth’s systems. You can read more about these here.

However, we are not on track to stay below 1.5C. If all countries who have signed international agreements to reduce their carbon emissions kept to these targets, which we are not currently achieving, we are expected to reach 2.7C of warming by 2100.