The changes that are expected ahead will happen much faster than the rate at which species and ecosystems typically are able to adjust. Plants and animals essentially would need to move about 1 yard each day farther north or higher in elevation to maintain the conditions they prefer. While farmers and others can shift where they grow crops, Field said, it's different for a butterfly or a maple tree.
"Maple trees are not good at moving. You don't have forests moving over long distances very, very fast."
Trees can shift over time when seeds are blown and squirrels carry acorns, but it typically is not that rapid, he said. The fastest that trees have had to move in the past was tens of meters per year. That's known from pollen records, he said.
"We actually don't have any good examples of them moving as fast as they'll need to in the future because the climate zones haven't moved that fast," Field said.
At the same time, species and plants will be affected by other human-induced changes.
"In responding to those rapid changes in climate, organisms will encounter a highly fragmented landscape that is dominated by a broad range of human influences," the study said. "The combination of high climate-change velocity and multidimensional human fragmentation will present terrestrial ecosystems with an environment that is unprecedented in recent evolutionary history."
The rapid pace of climate change, Field said, "really sets a schedule by which adaptation changes need to be made." That includes such moves as flood protection and building different kinds of structures.
Some of the changes to the planet cannot be stopped because the temperature increase is unavoidable. But the scientists emphasized that people do have the ability to affect the severity of the shifts.
To hold the temperature increase to about 1.5 degrees, the globe would need to cut its greenhouse gas emissions to zero by 2050, and then have negative emissions, meaning "the sum of all human activities is a net removal of CO2 from the atmosphere," the study says. If that happens, changes by the end of the century will be less severe, Field said.
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In about the last 100,000 years, there have been 23 abrupt temperature changes in Greenland ice cores. In those moments, the temperature abruptly jumped or fell 9 to 14 degrees Fahrenheit across the planet and 25 to 35 degrees Fahrenheit in Greenland. The changes typically took decades to generations, but at their most extreme, they only took two to three years.
Counterintuitively, published consensus statements on climate change do not factor in abrupt change -- an omission that seriously affects how climate policy is made. The reason is that we do not yet have the skill to model abrupt changes, even though ample robust evidence exists of the common occurrence of abrupt change in prehistory. It may seem unimaginable that these most important of all climate changes have been disregarded in climate policy, but this is the way the culture of the climate science consensus works. Policy is based upon impacts that we project to happen in the future through modeling.
Weather Models Are Not Climate Models
It's not that modeling cannot project the future. Climate modeling is actually quite accurate. It's weather modeling that goes awry after about five days.
However, there are major differences in techniques for predicting weather (in the near term) and predicting climate (over the long term). Weather models use the most recent weather data to project what the weather will be this weekend. Climate models can use weather data from any time frame, and then climate modelers create hundreds of model runs and average them all together to get climate projections.
Abrupt Change: How Do We Know When It Starts?
Modeling can't tell us when abrupt climate change is beginning, at least not to the satisfaction of the consensus community that creates our climate policy. So, how do we know if we are in the early stages of an abrupt shift? It sure seems that we are warming a lot faster than before. Is this an abrupt change? Are there things other than temperature that we can use to imply that we are changing our climate abruptly?
Because it takes time for science to gather data, and it takes 30 years of data for temperature records to become statistically meaningful because of all the natural variability in the weather, we must move to a different field of decision making to determine if we are in an abrupt change. We have to use circumstantial evidence.
Circumstantial Evidence Is Factually Meaningful
Really? Circumstantial evidence? Yes, circumstantial evidence is perfectly appropriate for making decisions. If we go to bed and there is no snow on the ground, then wake up and there is snow on the ground, circumstantial evidence tells us that it snowed overnight. If we were to have seen it snowing, this would be direct evidence, but -- at least in this situation -- direct evidence isn't necessary for us to have an idea of what happened: Circumstantial evidence is meaningful.
Can we look at temperature records to see if they are increasing faster than before and if this increase is meaningful? In a stable climate, the number of new high temperature records should be the same as the number of new low temperature records (1 to 1). From 1900 to the 1990s in the US, the number of new high vs. low temperature records was between 0.77 to 1 and 1.14 to 1, or really close to 1 to 1.
In the 1990s the ratio increased to 1.36 to 1; high records outpaced low records by 36 percent. In the 2000s the ratio was 2.04 to 1 -- twice as abundant. In the previous 365 days to April 1 (no joking), globally we saw 5,996 high temperature records and only 814 lows, or a ratio of 7.4 to 1. This is 700 percent more highs than lows, or seven times more. Not only is this number meaningful, the short amount of time that we have gone from stable to big-gulp radical is meaningful in an abrupt climate change way.
Forests Flip From Carbon Sink to Carbon Source
Another good way to understand if our climate is changing abruptly would be to look at our global ecosystems. Are they stable, or rapidly changing, and how do we determine if the changes are radical enough to be considered "abrupt?"
Across western North America, a single species of native beetle has been driven berserk because of warming. As recently as the 1990s, it took the mountain pine bark beetle (MPB) two years to raise a family. But today, summer is two-thirds longer than it was in our old climate; spring and fall come a month sooner and later, respectively, every year.
It is so warm that the MPB can now go through two life cycles a year, radically increasing the number of beetles on the attack. These little beetles are about the size of a grain of rice; up to 10,000 beetles can attack a single tree. However, since about the turn of the 21st century, the beetles have multiplied so quickly that they've killed 60 to 90 percent of 89 million acres of forest. This is 20 percent of western North American forests.
Our forests are undergoing an eco-regime change. The trees that live here now cannot cope with the insect populations enhanced by warming and they are being replaced by species that will be able to withstand the onslaught. The pine beetle attack in British Columbia alone has allowed forests in that region to go from a small carbon sink to a large carbon source. In the worst year in British Columbia, carbon emissions were equal to 75 percent of all carbon emissions from forest fires across all of Canada from 1959 through 1999.
The Amazon -- the greatest carbon dioxide sink of them all, the lungs of our world -- has flipped from a carbon sink to a carbon source; but for a different reason.
In 2005 the Amazon experienced a 100-year drought, and then in 2010, a drought significantly more extreme. Billions of trees were killed. Because dead trees do not absorb carbon dioxide and instead emit it as they decompose, instead of absorbing carbon dioxide and helping stabilize our ever-increasing climate pollution emissions, the Amazon is now emitting half as much carbon dioxide as Brazil emits every year.
Gulf Stream Shutdown: Abrupt Changes in Prehistory
Why did our climate change abruptly in prehistory? Mostly, the changes were caused by ice loss in the North Atlantic, from the great North American Ice Sheet that once covered New York City a mile thick with ice. The ice sheet created collapse events where great iceberg armadas were released into the North Atlantic. They melted and created a buoyant freshwater plug in the North Atlantic that slowed or stopped the flow of the Gulf Stream northward. The importance of this impact cannot be understated. The Gulf Stream is very likely the most important ocean current on earth. At its peak off of Cape Hatteras, it transports 150 sverdrups, or 21 cubic miles of water, per day. Farther north, without the warming influence of the Gulf Stream, the ocean cooled and froze. The increased ice and snow reflected more sunlight back into space without it warming the planet. An abrupt fall in temperature ensued.
As of 2015, Gulf Stream flow has decreased by 40 percent because of a massive pool of buoyant fresh water in the North Atlantic from Greenland where ice loss has increased 500 percent since the turn of the 21st century. But this fresh water plug creates abrupt cooling, correct?
Well, it does when the Earth's CO2 concentration is below 280 ppm. Right now, CO2 is simply too high (400 ppm). Gulf Stream shutdown will not (likely) cool off the northern North Atlantic enough for it freeze.
Feedback Loops Rule Abrupt Climate Change
May snow cover across the Northern Hemisphere has fallen about 25 percent since 1980. This might seem like a small thing, but snow reflects 90 percent of the sun's rays back into space, whereas earth, rocks, water, plants, etc. absorb 90 percent of the sun's rays and change it into heat that gets trapped on Earth by the greenhouse effect.
This is called the "albedo feedback," and it is responsible for high latitudes and high altitudes warming at a rate that is double to quintuple the rate found at lower latitudes. A little bit of warming melts more snow, which absorbs more heat, which melts more snow -- in a chain reaction.
There are many warming feedback loops. Temperature itself creates one. The warmer it gets, the drier it gets. Drier air can warm more than moist air.
Dying forests create a feedback loop, too: As large numbers of trees die, less CO2 is absorbed, creating more warming, which in itself allows more trees to become more stressed, which gives insects a greater advantage in killing trees.
The Gulf Stream shutdown also creates a feedback loop. The North Atlantic is where the Gulf Stream sinks into the abyss. As it sinks, it carries carbon dioxide with it and much of it gets removed permanently by different biological and geochemical means. When the Gulf Stream shuts down, this primary source of ocean carbon sequestration goes away. More CO2 stays in our atmosphere, creating more warmth, which then increases the pool of fresh buoyant Greenland ice loss water in the north Atlantic that blocks the Gulf Stream more, keeping more and more CO2 from being buried in the abyss by deep water formation.
Other new science that is extraordinarily meaningful to abrupt climate change could be far more pertinent than the small amount of space here allows description. In particular, Antarctica has begun initiation of collapse, which could result in 10 feet of sea level rise in 35 to 45 years if upper-ocean warming around Antarctica is not returned to zero by that time.
Until we implement a rule or law that regulates climate pollution like we regulate all other forms of pollution on this great planet, uncertainty, doubt and apathy will rule. Until we finally implement this policy we have been attempting to implement for over 20 years, nothing will change. Except warming.
Note: Detailed references for the claims in this article can be found here.
Bruce Melton is a professional engineer, environmental researcher, filmmaker, author and CEO of the Climate Change Now Initiative in Austin, Texas. The Climate Change Now Initiative is a nonprofit outreach organization reporting the latest discoveries in climate science in plain English. Information on his book, Climate Discovery Chronicles, can be found along with more climate change writing, climate science outreach and critical environmental issue documentary films at ClimateDiscovery.org. Images copyright Bruce Melton and the Climate Change Now Initiative except where referenced otherwise.