The potential future of our planet could be worse than what climate models have predicted. According to the latest analysis, global warming may actually turn out to be twice as warm than current projections estimate, reveals a new study.
Conducted by scientists from 17 countries, the research was published last week in the journal Nature Geoscience and paints a worrying picture of the future Earth under the influence of global warming.
A green Sahara Desert, collapsing polar caps, a 20-foot (six-meter) sea-level rise — this is what the future may have in store, Science Daily reports.
And that’s even if the world strives to meet the Paris Climate Agreement, the global action plan signed in December 2015 with the goal to limit global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, notes USA Today.
As study co-author Alan Mix puts it, the Paris agreement — of which President Donald Trump dropped out in 2017, as reported by the Inquisitr — may not be enough to veer the planet away from a catastrophic path.
“Even with just 2 degrees of warming — and potentially just 1.5 degrees — significant impacts on the Earth system are profound.”
For one thing, the rise in global sea level alone could bring about disastrous consequences.
“We can expect that sea-level rise could become unstoppable for millennia, impacting much of the world’s population, infrastructure and economic activity,” said Mix, who is a professor at the College of Earth, Ocean, and Atmospheric Sciences of the Oregon State University.
— Phys.org (@physorg_com) July 5, 2018
Warning From The Past
These conclusions come from an investigation into the natural global warming periods of our planet’s history, which can help shape scenarios for the future.
To see what lies ahead, the scientists looked to the past and analyzed three warm periods going back in time as far as 3.5 million years ago.
These are some of the best documented global warming periods in the Earth’s existence, shows Science Blog, and refer to the Holocene thermal maximum (which occurred 5,000 to 9,000 years ago), the last interglacial (that took place between 129,000 and 116,000 years ago), and the mid-Pliocene warm period (recorded some 3.3-3 million years ago).
During all that time, Earth’s climate was 0.5 to 2 degrees Celsius warmer than in the pre-industrial 19th Century — a warming brought on by changes in our planet’s orbit in the case of the first two, more recent, global warming events.
The mid-Pliocene global warming, however, was triggered by carbon dioxide (CO2) in the atmosphere, present at concentrations of 350 to 450 parts per million — which is essentially more or less what we see today.
By looking at various assessments pertaining to paleoclimate methods, such as measurements of ice cores and atomic isotopes used for dating, as well as sediment layers and fossil records, the team got a good idea of the combined effects of the three warming periods.
What they uncovered was that climate change in the Earth’s past produced an entire list of tragic consequences, starting with the collapse of polar ice caps, the major retreat of ice sheets in Antarctica and Greenland, a sea level rise by a least 20 feet, and significant changes in the entire marine ecosystem on account of a major plankton redistribution — and that’s just to name a few.
Perhaps the most striking of all was seeing the Sahara Desert become greener, high altitude forest species start to decline, and the edges of tropical forests give way to fire-dominated savanna.
The image below, tweeted by study co-author Dr. Nerilie Abram of The Australian National University and the ARC Centre of Excellence for Climate Extremes in Australia, reveals a more detailed look at the past effects of global warming.
Our Warmer Worlds review paper out now in @NatureGeosci:
"Palaeoclimate constraints on the impact of 2°C anthropogenic warming and beyond"@PAGES_IPO @ClimateSystem @ClimateExtremes @anuearthscience pic.twitter.com/jFszQy1E8A
— Dr Nerilie Abram (@dr_nerilie) June 25, 2018
The study also revealed that these effects were enhanced by what the scientists are calling “amplifying mechanisms,” which are not accurately reflected by climate models and which actually make the situation even worse than expected.
“Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections,” said study lead author Prof. Hubertus Fischer, an expert in climate and environmental physics at the University of Bern in Switzerland.
So, what does this mean for the future?
Well, since Earth is now warming at a much faster rate than it did during any of the three global warming events in the past, while human-caused CO2 emissions are only increasing — and have reached a 60-year high in April, the Inquisitr reported at the time — the future is looking foggy.
According to the study, even if we put an end to CO2 emissions right now, the planet won’t reach an equilibrium until after centuries, possibly even millennia.
“This suggests the carbon budget to avoid 2°C of global warming may be far smaller than estimated, leaving very little margin for error to meet the Paris targets,” Fischer points out.
The Fault With Current Climate Models
So, what caused the discrepancy in our current climate models?
As study co-author Prof. Katrin Meissner explains, these climate models get the job done when it comes to short-term effects of climate change.
“Climate models appear to be trustworthy for small changes, such as for low emission scenarios over short periods, say over the next few decades out to 2100.”
The trouble starts when you have to adjust the equation to factor in “more persistent” effects; this is where the predictions “underestimate climate change,” says Meissner, who runs the Climate Change Research Centre at the University of New South Wales in Australia.
“As the change gets larger or more persistent, either because of higher emissions, for example a business-as-usual-scenario, or because we are interested in the long-term response of a low emission scenario, it appears they underestimate climate change.”