Earth’s Climate — Year 2300

Although we won’t be around to experience earth’s climate in the year 2300 in person, a computer-simulation study released by Lawrence Livermore National Laboratory in January, 2013, takes us to that future world. According to the Livermore team, led by physicist Govindasamy Bala, 2300 is when the world’s supply of fossil fuels will likely be depleted. No more oil, coal, or natural gas. What will the world look like at that point? Bala’s team used a combination of climate and carbon-cycle computer simulations to find out.

According to the study, the world will be much hotter. Average world temperature will increase by 8°C (14°F). Arctic temperature will increase a whopping 20°C (36°F). The polar cap, the Greenland Ice Sheet, and the Arctic tundra will have melted. Instead of ice and snow, boreal forest will cover the land, and Arctic seas will be ice free. Tropical vegetation will also expand, as present-day temperate areas become hotter.  

Parts per million of CO2 in the air will triple. From the present approximately 400 ppm of CO2, our atmosphere will be saturated with 1,200 ppm of CO2, bringing the world close to some prehistoric CO2 levels.

There will come a time when the oceans can no longer absorb CO2.The world’s oceans now function as a carbon sink, eventually absorbing 80% of the CO2 in the atmosphere. But the more CO2 the oceans take in, the higher the acid content of the water becomes. Computer simulations predict that extreme acidification will wipe out much of marine life, including hundreds of food fish species, and destroy the world’s coral reefs. The destruction of coral systems will hamper the ocean’s ability to absorb additional CO2. With the oceans no longer able to absorb CO2, about 45% of the emitted carbon dioxide will remain in the atmosphere, intensifying the heating of the planet.

The melting of glaciers and polar ice will eventually raise world sea level by 7 meters (34 feet). Many populated islands will be under water, as will many of the world’s major port cities. The sea level rise will be gradual, but populations on low-lying islands and in seacoast communities should start preparing for the future.

According to physicist G. Bala, it is now evident that a great deal of damage has already been done. Years of unrestricted carbon pollution has started a process called committed warming. Bala said, “No matter what we do – even if we completely stop burning fossil fuels today – we are committed to future increases in global temperature … Our present trajectory is risking severe environmental damage that could last for hundreds of years.”

Is there anything we can do to reverse the trend? Even though committed warming is already in motion, reducing carbon emissions as much as possible and as quickly as possible can hopefully still serve to mitigate future damage. The Livermore team is using integrated computer simulations to assess to what extent and how soon the damage can moderated, depending on pace of emissions reduction. It is urgent that the governments and industries of the world take note, and shift their emission reduction efforts into high gear.

 

Are Longer, Hotter Droughts Here to Stay?

In the summer of 2012, 81% of the land area of the contiguous 48 states was in some stage of drought, from Abnormally Dry to Exceptional Drought, according to the US Department of Agriculture. Half the counties in the US — 1,600 counties in 32 states — were declared natural disaster areas by USDA*.

Hot winds, wildfires, and temperatures as high as 110°F (43°C} were recorded in many areas. Crop failures were widespread. Of the crops that survived, yields were expected to be less than half of normal. Lake, river, and reservoir levels were dropping to record lows. 76% of the corn crop was in less than good condition. A smaller US crop yield was expected to result in price increases for a wide range of food products, and contribute to worldwide grain shortages.

Was this extreme and prolonged drought part of a natural cycle, occurring every 40 to 50 years as it had in the past, or did it signal a new trend toward longer, hotter, and more frequent severe drought events?  A research paper published in Proceedings of The National Academy of Sciences presents data showing that these extreme events have occurred far more often in the past 30 years than they did in the prior 30.

The paper, authored by James Hansen of NASA’s Goddard Space Flight Center, compared worldwide surface temperatures recorded from the period 1950-1980, with those from 1980-2010. Using a Bell Curve to compare the data from the two periods, the NASA scientists found that during the 1950-1980 period, 33% of earth’s land area experienced summers defined as “hot”, “very hot”, or “extremely hot”. During the 1980-2010 period, 75% of land area experienced “hot” to “extremely hot” summers, a 225% increase. The data indicated that drought is not only now more widespread, but occurs more frequently than in the past, and with hotter temperatures.

Is global warming the main cause of this rapid shift toward a hotter world? Hansen and his colleagues say that no natural cycle could cause this much change this fast without outside influence.  They believe that global warming, speeded up by the tremendous volume of human-produced greenhouse gasses pumped into the atmosphere, is largely responsible for this quick transition to a hotter earth. Can we slow this process by reducing greenhouse gas production, or are we already past the tipping point? No one knows for sure.

*USDA Drought Intensity Scale based on historical records of drought length and severity: D0-Abnormally Dry (occurred every 3 to 5 years on average), D1–Moderate Drought (5 to 10 years), D2–Severe Drought (10 to 20 years), D3 – Extreme Drought (20 to 50 years), and D4-Exceptional Drought (50 years).