Nav: Home

Lessons about a future warmer world using data from the past

June 25, 2018

CORVALLIS, Ore. -- Selected intervals in the past that were as warm or warmer than today can help us understand what the Earth may be like under future global warming.

A latest assessment of past warm periods, published today in Nature Geoscience by an international team of 59 scientists from 17 nations, shows that in response to the warming ecosystems and climate zones will spatially shift and on millennial time scales ice sheets will substantially shrink.

The study was an outcome of a workshop that took place in Bern, Switzerland and was coordinated by the University of Bern, the University of New South Wales in Australia, and Oregon State University.

The compiled evidence from the past suggests that even with a global warming limited to within 2 degrees Celsius above preindustrial levels, as aimed at in the Paris Agreement, climate zones and ecosystems will shift, rapid polar warming may release additional greenhouse gases, and sea-level will rise by several meters over several thousand years. These observations show that many current climate models designed to project changes within this century may underestimate longer-term changes.

Over the past 3.5 million years, several time intervals are known for being .5 to 2 degrees Celsius warmer than the so-called preindustrial temperatures of the 19th century. These intervals reveal much stronger regional warming at high latitudes than in the tropics, similar to what models predict for a 2 degrees Celsius global warming by the year 2100. Although not all these past warmings were caused by higher carbon dioxide concentrations, they are helpful to assess the regional effect of a warming of a scale comparable to that aimed at in the Paris Agreement.

Ecosystems and climate zones will generally shift poleward or to higher altitudes. In response, permafrost thaw may release additional carbon dioxide and methane to the atmosphere, driving additional warming. Past observations suggest that if warming can be limited to no more than 2 degrees Celsius as proposed by the Paris accords, the risk of catastrophic runaway greenhouse gas feedbacks is relatively low. Nevertheless, the significant amount of additional carbon dioxide released from permafrost and soils must be considered in future emission budgets.

"Accounting for the additional release of CO2 leaves even less room for error or delay as humanity seeks to lower its CO2 emissions and stabilize global climate within reasonable limits," Hubertus Fischer, of the University of Bern, said.

Even a warming of 1.5 to 2 degrees Celsius above preindustrial levels will be sufficient to trigger substantial long-term melting of ice in Greenland and Antarctica and sea-level rise of more than 6 meters that will last for thousands of years. Rates of sea-level rise higher than those of the last decades are likely.

Alan Mix of Oregon State University noted the importance of this sea-level rise, stating, "we are already beginning to see the effects of rising sea level. This rise may become unstoppable for millennia, impacting much of the world's population, infrastructure, and economic activity that is located near the shoreline."

Comparison of observations of the past with computer simulations suggests that models may underestimate long-term warming and its amplification in polar regions.

Katrin Meissner of University of New South Wales, Australia, said that, "while climate model projections seem to be trustworthy when considering relatively small changes over the next decades, it is worrisome that these models likely underestimate climate change under higher emission scenarios, such as a 'business as usual' scenario, and especially over longer time scales."

According to the researchers, this information from the past underscores the urgency of reducing carbon dioxide emissions soon to meet the Paris Agreements in this century and beyond.

The publication in Nature Geoscience is a result of the Past Global Changes integrated activity "Warmer Worlds" that uses paleoclimate evidence to assess a future warming. To this end the Warmer Worlds activity assembled about 50 renowned international researchers in April 2017 for a workshop in Bern, Switzerland funded by PAGES and the Oeschger Centre for Climate Change Research of the University of Bern. The publication is the outcome of this expert assessment.
-end-
The Warmer Worlds activity is coordinated by Fischer, Meissner and Mix. PAGES, a network funded jointly by the U.S. and Swiss National Science Foundations, is a core project of the global sustainability program Future Earth and has the goal to coordinate and promote past global change research.

Oregon State University

Related Climate Zones Articles:

Orbital variations can trigger 'snowball' states in habitable zones around sunlike stars
Aspects of an otherwise Earthlike planet's tilt and orbital dynamics can severely affect its potential habitability -- even triggering abrupt 'snowball states' where oceans freeze and surface life is impossible, according to new research from astronomers at the University of Washington.
Hurricane Harvey: Dutch-Texan research shows most fatalities occurred outside flood zones
Scientists found that most Houston-area drowning deaths from Hurricane Harvey occurred outside the zones designated by government as being at higher risk of flooding: the 100- and 500-year floodplains.
Rethinking the fight as surge of malaria deaths in conflict zones threatens to upend progress
Ten years of progress globally in the fight against malaria have masked the rapid rise of infections and deaths in African countries experiencing conflict and famine, though new strategies implemented in places like the Central African Republic, South Sudan, and northern Nigeria could provide a way forward, according to research presented this week at the 7th Multilateral Initiative on Malaria (MIM) Pan African Malaria Conference.
X-rays could sterilize alien planets in (otherwise) habitable zones
Intense radiation could strip away the ozone layer of Earth-like planets around other stars and render them uninhabitable, according to a new study led by Dr.
No-fishing zones help endangered penguins
Small no-fishing zones around colonies of African penguins can help this struggling species, new research shows.
Why Japan's coastal zones might be disappearing due to climate change
Climate change can cause a range of effects on coastal environments, such as a decrease in sediment supply, changes in the intensity and frequency of extreme events, and changes in sea levels and wave climate.
Slow earthquakes in ocean subduction zones shed light on tsunami risk
Understanding 'slow-slip' earthquakes on the seafloor -- seismic events that occur over a period of days or weeks -- is giving researchers new insights into undersea earthquakes and the subsequent creation of tsunamis.
Variable speed limits could reduce crashes, ease congestion in highway work zones
As the summer months approach, most people turn to thoughts of sunshine, outdoor barbecues and destination trips.
For plastic surgeons, learning 'danger zones' can increase safety when using facial fillers
Dermal fillers have become a popular alternative to surgery for patients who want a younger facial appearance.
Dead zones may threaten coral reefs worldwide
Dead zones affect dozens of coral reefs around the world and threaten hundreds more according to a new study by Smithsonian scientists published in Proceedings of the National Academy of Sciences.

Related Climate Zones Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#513 Dinosaur Tails
This week: dinosaurs! We're discussing dinosaur tails, bipedalism, paleontology public outreach, dinosaur MOOCs, and other neat dinosaur related things with Dr. Scott Persons from the University of Alberta, who is also the author of the book "Dinosaurs of the Alberta Badlands".