by David Holmes
Two degrees – the temperature rise we need to stay under to avoid catastrophic effects of climate change – is now the catch cry for global warming. Governments and numerous NGOs have eagerly adopted the limit; whether we can meet the target is another matter. But 2C isn’t an easy concept to grasp. So, how can we imagine what 2C means for the world?
First, why is 2C so significant? At any time of the year, for most latitudes at which people live, the difference between overnight lows and daytime high temperatures can be as much as 15C. In summer it is even greater. When the day to day temperatures of weather vary so much, 2C seems insignificant.
What we’re talking about here, though, is the global average temperature, not daily variations – and we’re fast approaching 2C warmer than before the industrial revolution and emissions from fossil fuels intensified. With feedbacks, such as increased water vapour (which is a powerful greenhouse gas), loss of reflective ice surface, and potential methane pulses (a greenhouse gas 20-times more powerful than CO2), 2C could be reached before 2060.
But it’s very difficult for people to imagine what a change in average temperature of 2C means for the planet as a whole, because of that daily variation.
One way is to imagine what the world was like when it was 2C colder than 1750. Fortunately, the earth has already done the experiment for us, 18,000 years ago in the ice ages.
For starters, there was an ice sheet one mile thick (the Laurentide) that extended over the northern half of North America right down to New York.
But these events happened 18,000 years ago, over a timeframe of hundreds of years, as a result of changes in the earth’s orbit and other natural forces.
What should worry us today is that human-forced climate change is happening at 10,000 times the rate of climate change caused by these natural cycles.
The changes we’re seeing now may be happening quickly compared to the past, but still slowly compared to human lifespans. That’s because the climate system is “lethargic”. And here’s the problem, the inertia of climate is very difficult to imagine or visualise.
There a variety of reasons visualising the inertia of climate change is difficult; prime among them being that climate is complicated. There’s a complex interplay between climate and oceans. For instance, 90% of warming is going into the oceans – at the rate of four Hiroshima bombs per second. But even with all that heat going in the oceans, they will still take a great many decades to warm.
The other complexity is the relationship with ice and climate. Ice may be melting at the poles, but it may be having surprising effects in the Northern hemisphere, like more cold fronts.
And as the atmosphere warms it can hold more water vapour, which can lead to increased rainfall and even snow at higher latitudes.
So we need an image that captures the complexity of the climate system as it gradually approaches 2C, and that climate won’t always appear to warm in a straightforward manner. One way is to think of the planet as a kind of open icebox which has been neglected at a party. The ice inside reacts to the warmer climate outside and melts. As it melts, the resultant water remains cold until all the ice has melted. Eventually the icebox fails to prevent the drinks from heating up.
According to climate scientist James Hansen, we are never going to see another ice age, ever. When the ice melts it will not be replaced. Ice extent will fluctuate from year to year, and some climate change deniers will selectively point to recovery years, but there is only a downward escalator. Which means, unless dangerous climate change is addressed, for some of us today, and many more tomorrow, the party will definitely be over.
This article follows Four Hiroshima bombs a second: how we imagine climate change. Read ithere.
Dr David Holmes works in the School of Communications and Media Studies in the Faculty of Arts at Monash University.
This article originally appeared on The Conversation.
Monash students star at the Ossie Awards
Death or Liberty tours in London, Dublin and Wales
“Democracy wasn’t granted in the 1850s and late 19th century simply because some wise politicians … Continue reading Death or Liberty tours in London, Dublin and Wales
Music Industry Survey: Investigating the Value of Music Exports
At a time when Australian pop, rock, country and hip hop acts are finding new … Continue reading Music Industry Survey: Investigating the Value of Music Exports
Growing inequality in the US is bad news for climate change
David Holmes, Monash University This week’s US Presidential election will likely be more important for … Continue reading Growing inequality in the US is bad news for climate change
‘We must keep the lights on’: how a cyclone was used to attack renewables
David Holmes, Monash University The mid-latitude cyclone with no name that hit South Australia last … Continue reading ‘We must keep the lights on’: how a cyclone was used to attack renewables
Don’t stop the music: making and breaking a ‘Music City’
Is there a formula for making a ‘Music City’ like Melbourne? And if there were a formula, could you export it and create a new one, and how authentic would it be? Monash researcher Shane Homan and his team are looking at these questions and more.
Why has climate change disappeared from the Australian election radar?
David Holmes, Monash University Two weeks into a protracted election campaign, it is looking ever-more … Continue reading Why has climate change disappeared from the Australian election radar?
The Monash Media Lab: a great place to learn
Head of School, AP Mia Lindgren, and TV presenter and academic, Waleed Aly, talk about what makes the new Lab so important for students of Media, Film and Journalism.
Dr Andy Ruddock launches Youth and Media book in Serbia
Monash University’s senior lecturer in Communications & Media Studies, Dr Andy Ruddock, recently launched the Serbian version of his … Continue reading Dr Andy Ruddock launches Youth and Media book in Serbia
Master of Communications and Media Studies graduate Jason Ng
Jason explains how the industry insights he gained in the degree led him to a new research interest and career pathway
Australian television premiere of ‘Death or Liberty’
An Empire’s rebels banished to the end of the earth: a documentary brings to life a forgotten history of convict rebels.
Meet the fossil fuel firms sponsoring the world’s biggest climate conference
Dr David Holmes, senior lecturer in Communications and Media Studies at Monash, is in France for the Paris Climate Summit and will be reporting regularly on the events.