Why half a degree matters with climate change
Our earth has warmed around 1⁰C (1.8⁰F) since the 19th century. But what does that mean for our planet, and what happens as it continues to rise?
Global warming of 1⁰C – today
A one-degree global change is incredibly significant — it takes an enormous amount of heat to warm oceans, atmosphere and land right across the world. Our planetary systems are finely balanced and a degree of temperature change has a massive impact.
To put a one-degree change in context, a three-degree drop could plunge the Earth back into the ice age, whereas a three-degree rise could introduce a hothouse situation — an irreversible state of heating and natural disaster.
In 2015, 174 nations around the world agreed to the terms of the Paris Agreement — an agreement to keep global warming well below 2⁰C. But in 2018, the Intergovernmental Panel on Climate Change (IPCC) warned that we could be on track to miss that target by a long way…
Here’s a breakdown of what the IPCC expects to happen as the planet continues to warm up.
Global warming of 1.5⁰C — the threshold
Life at 0.5⁰C above Earth’s current temperature:
– Sea ice remains during most summers
– 14% of the world’s population exposed to ‘extreme heat’
– 350 million+ people in urban populations exposed to severe drought
– 8% of plant species lose over half their range
– 31–69 million people exposed to flooding from rising sea levels
This 0.5⁰C temperature increase is considered the ‘safe’ threshold. Anything above this significantly increases the risk of extreme weather events, sea level rise, droughts, poverty and mass migration.
Holding warming to 1.5⁰C will require a ‘staggering transformation’ of the global energy system and wide scale change across society, but it’s not impossible. We can all play a significant part in keeping earth’s temperature at a non-threatening level, but we need to act now.
Global warming of 2⁰C — the upper threshold
Life at 1⁰C above current temperature:
– Ice-free summers are 10 times more likely
– 37% of the world’s population exposed to ‘extreme heat’
– 411+ million people in urban populations exposed to severe drought
– 16% of plant species lose over half their range
– 32–80 million people exposed to flooding from rising sea levels
An extra degree of warming would push life on our planet to extremes. To stay below 2⁰C, it’s estimated that emissions have to decline to zero by 2075 or before.
Global warming above 2⁰C — Hothouse Earth?
Warming of over 1⁰C above our current temperature could risk us reaching a hothouse state.
Earth’s last hothouse state was in the Cretaceous period, 100-million years ago. With warming of over 2 degrees, self-reinforcing feedbacks — wildfires, methane release, forest dieback, melting ice caps and so on — could drive the temperature toward runaway heating, a nonlinear process that no amount of human intervention can control.
Where do we go from here?
The good news is that we can reverse this – but we must take action now.
The organisations we support at The Crowd are already working hard on the solutions to the climate crisis. If you’re looking to make an impact, head over to our organisations page to learn more about the amazing organisations you can support with a single monthly donation.
We’ve also written a handy guide to fighting climate change in your day-to-day life, which you can read here.
