Global climate change

Future global warming may be double than what current climate models predict

By Brett Anderson, AccuWeather senior meteorologist

7/10/2018, 12:03:02 PM

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A new peer-reviewed study published in the journal Nature Geoscience concludes that global warming may eventually be twice as warm as what current climate model consensus indicates.

This international study also states that global sea level rise may reach six meters or higher even if the world meets the established 2 deg. C. rise target, which was established by the Paris accord.

The research focused on observational evidence from three different warm periods going as far back as 3.5 million years, according to the UNSW Sydney (AU) report.

Long term atmospheric CO2 concentration.

“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 lead author, Prof Hubertus Fischer of the University of Bern.

The research team looked at the Holocene Thermal Maximum, the last Interglacial and the mid-Pliocene periods.

The Holocene and the last Interglacial were caused by predictable changes in the Earth's orbit, but the mid-Pliocene was a result of high carbon dioxide concentrations that were similar to what we see today.

These three periods give strong evidence of how a warmer Earth would appear once the climate had stabilized. By contrast, today our planet is warming much faster than any of these periods as human caused carbon dioxide emissions continue to grow. Even if our emissions stopped today, it would take centuries to millennia to reach equilibrium, according to the report.

Key excerpts from the UNSW Sydney report..........

“Even with just 2°C of warming – and potentially just 1.5°C – significant impacts on the Earth system are profound,” said co-author Prof Alan Mix of Oregon State University.

“We can expect that sea-level rise could become unstoppable for millennia, impacting much of the world’s population, infrastructure and economic activity.”

“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. However, 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,” said co-author Prof Katrin Meissner, Director of the University of New South Wales Climate Change Research Center.