If COVID-19 has shown us anything - we’ve got to get better at understanding, and trusting,
science. Scientists had been warning us for decades about the risks of a global
‘pandemic’. And what did many countries do? Well, some countries had previously
removed or defunded institutions that would have helped their citizens deal
with this COVID-19 pandemic, when it finally hit the world.
And for an even longer time - over 60 years - climate scientists have been warning us about
climate change. Like pandemics, climate change is also something we didn’t really pay much attention
to – until now, when it’s arguably already a bit too late! While the impact of COVID-19 was sharp
and something we humans could react to - somewhat - quickly, climate change is slower but arguably
deadlier. The last few years have been the hottest years on record for many places in the world,
with extreme weather events destroying lives and livelihoods becoming shockingly commonplace.
When most people hear ‘climate change’ or ‘global warming’ – which are different things, yet often
used interchangeably – they imagine the gigantic polar ice caps melting and flooding the planet;
sinking Miami, Jakarta, Bangkok and Venice.
And while scientists agree this is a real possibility – melting ice flooding everything
isn’t actually the main threat that should be keeping you up at night.
The world’s getting hotter, and 97 out of every 100 currently publishing climate scientists
blame human activity for the melting ice. Since the climate is such a complex system, we’re not
100% sure about exactly how a real disaster might happen – just like we couldn’t quite predict the
scale and scope of this COVID-19 pandemic. But one thing is for sure - sea levels will rise.
You see, in the 1990s - the Earth used to melt 760 billion tonnes of ice every year. Since 2010s,
this has been increased to 1.2 trillion tons per year - a 60% increase within my lifetime.
Now, some of this ice is turning from ice to liquid underwater, which means sea levels aren’t
directly impacted. But there is a lot of ice that isn’t underwater… and if this ice all melted,
the sea level would rise 70 meters...about 230 feet.That’s
about enough to cover London’s Tower Bridge twice over, or drown the entire Taj Mahal.
OK – that’s a lot of water, but can’t we just move away from the coasts?
The issue is – humanity loves water. We need it. We’ve built civilisations around
water sources, and half of the world’s population lives in coastal regions.
And we’re not just talking about small fishing villages – we’re talking about the biggest
cities in the world –Tokyo, New York, Chittagong, Sao Paolo, Mumbai; and so many more.
Even a tiny rise of - not 70 meters - just one single meter would cause
catastrophic damage globally. A 10 meter rise (33 feet) would displace 10% of all the human
beings on the planet (630 million people)), 25m would displace 20% of us and the full
70m would drown out all of Bangladesh, most of Northern China, create an entire new
sea inside Australia. There would be no Miami, London, Venice, Netherlands.
Remember when we said sea levels rising aren’t even the biggest problem? Well,
the ice in the Antarctic and Arctic is all freshwater ice, like you find in rivers.
The ocean, surprise surprise, is salty, which is over 97% of the earth’s water.
Why does this matter?
Because of ocean currents. The movement of water.
Ocean currents directly affect all our lives, they determine our weather,
the climate, even how we get most of the oxygen we breathe.
The ocean currents and the Earth’s wind systems move heat from the equator to
the cold poles of the earth, a bit like an engine. This ‘Great
Ocean Conveyer’ as it’s called is very important for our climate; a worldwide ‘circulation system’
for our planet. It’s also called the Thermohaline circulation system,
thermo meaning temperature and haline referring to the salt content. These two elements determine how
dense the water is. Remember all this ice, this freshwater ice, melting into the salty oceans?
That reduces the salinity or saltiness of the ocean through diluting it, which
reduces the density of this ocean water, which affects thermohaline circulation.
You see, thermohaline circulation relies on the cold, dense water sinking deep into the
ocean. But as global warming makes the water at the surface less salty, it can
prevent cold water from sinking, which stops the Great Ocean Conveyor from working properly.
All these changes and messiness will impact the Earth in different ways,
and some of this is hard to predict. Europe, for example, has always been weirdly warm, considering
for example that the city of London in the UK (picture of warmer london) is on the same latitude
as the freezing cold city of Quebec in Canada. This is because of the Gulf Stream, an important
piece of the Great Ocean Conveyor which moves warm water from the hot tropics straight to Europe.
You’d expect dramatic weather events and changes to be happening more often due to changes in ocean
currents; for example stronger hurricanes which cause more floods on top of the floods already
being caused by melting ice. Some areas would have a lot more rain while other areas would dry out.
.
On the Indian subcontinent, the disruption might mean a bigger temperature difference between
the land and sea in the tropical regions, affecting its yearly Indian monsoons and
so creating devastating floods and droughts. The same melting ice-caps could also disrupt
the all important African Monsoons and bring even more droughts throughout the continent of Africa.
This sort of volatility is particularly dangerous for agriculture
– food instability leads to famines and increasing poverty. As a result,
mass migration could collapse world governments and just make life really hard for us
all – and we’ve just had a tiny, small taste of that during this pandemic.
On top of all of that, this Ocean Conveyor moves nutrients along with it,
and as it just so happens, plants and plankton in the ocean are where we get over 50% of our oxygen
from. And it gets worse. All that melted ice would release CO2 into the atmosphere,
because ice needs high CO2 to melt in the first place. So not only do we affect the amount of
oxygen in the air by messing with water - oxygen we need to breathe-; by messing with
ice we’d also be increasing CO2 levels even more, meaning the ice melts even quicker.
To wrap up, while scientists have different views on the impact climate change will have
on the ocean conveyor system – one thing is absolutely clear,
we really don’t want to mess with the thermohaline circulation system, people!
Now you know exactly why melting ice is a threat to humanity – please share the link to
this video to your social media and spread the word! It’s really important that more
of us understand how all of this works.