Smoky air offers a dramatic sunset over a farm west of Junction City, Oregon, Thursday, Aug. 3, 2017, after a day of triple-digit temperatures and unhealthy air quality in the Willamette Valley.

(Brian Davies/The Register-Guard via AP)

At a Glance

Scientists say climate models cannot foresee all that will happen as global warming advances. "The further and faster the Earth's climate system is changed, the greater the risk of surprises," the scientists note.

Scientists working on a congressionallymandated report on climate change say changes to the Earth from global warming may trigger surprisesthat could have significant impacts on humanity.

The was compiled by 13 government agencies. Published online in January, the report has received attention this week after a copy of the report was published by the New York Times.

While the report confirmed what we know –climate change is real, human-caused and will continue to influence life on Earth –the scientists notethat there will be some surprises that climate models just can't predict.

"Humanity is conducting an unprecedented experiment with the Earth's climate system through emissions from large-scale fossil-fuel combustion, widespread deforestation and other changes to the atmosphere and landscape. While researchers and policymakers must rely on climate model projections for a representative picture of the further Earth system on these conditions, there are still elements of the Earth system that models do not capture well," the report says. "For this reason, there is significant potential for humankind's planetary experiment to result in unanticipated surprises —and the further and faster the Earth's climate system is changed, the greater the risk of such surprises."

The report notes two types of potential surprises that could significantly impact humanity. The first is compound events, where multiple extreme climateevents such as consecutive floods in the same region or a wildfire followed by heavy rainfall, occur simultaneously or sequentially and cause even greater disasters than can be anticipated.

Some areas are more susceptible to multiple types of extreme events occurring simultaneously, the report notes, such as an area prone to both floodings from coastal storms andriverine flooding from snow melt.

Compound events can surprise by being stronger, longer-lasting and more widespread thanmodel simulations are able to predict.

One example would be simultaneous drought events in different agricultural regions across the country, or even around the world, that challenge the ability of humanity to provide adequate affordable food. Regions that lack the ability to adapt would be most vulnerable to this risk,the report says.

The second type of surprise is "critical threshold or tipping point events," where some threshold is crossed in the climate system, leading to greater impacts.

"Some Earth system components, such as arctic sea ice and the polar ice sheets,may exhibit thresholds beyond which these self-reinforcing cycles can drive the components, or the entire system, into a radically different state," the report says.

Tipping points include the strengthening of El Nino and La Nino events, yearlong melts of the Arctic Sea Ice and melting of the permafrost, which would release CO2, further impacting global warming.

(MORE: )

Other tipping points that could impact the future include undersea methane releases. The reportsays there are as many as 3,000 gigatons of carbon in methane hydrates frozen in undersea sediment that could be released by warming water into the atmosphere, which would impact global warming more than is projected today.

The report also notes that there could very well be surprises in computer models that predict the impacts of global warming, especially in polar regions.

“Future changes outside the range projected by climate models cannot be ruled out,” the report says. “And climate models are more likely to underestimate than to overestimate the amount of long-term future change.”

The scientistsnote that climate surprises are nothing new. The discovery of the hole in the ozone layeris one such example. Within an 11-year period, atheory that chlorofluorocarbons depleted the ozone layer becamefact. That rapid discovery led to the Montreal Protocol to phase out CFCs. Another surprise turned out to be how quickly the decline in sea ice occurred, which turned out to be far sooner than predicted.

One takeaway from the report is that as global warming continues, the resulting consequences to the Earth will create unanticipated scenarios that have yet to play out.

The scientists point out that while the probability of these scenariosmay be difficult to assess, their "consequences could be high, potentially exceeding anything anticipated by climate model projections for the coming century."