Warning: This blog will have nothing to do with politics -- no mention of “cap-and-trade,” carbon taxes or “Climategate.” It’s the science that matters to me.
We had a little fun Friday night with the House Call, since it’s impossible to talk about global warming (or climate change) in the two minutes we get on the news. In a way, it’s a satire on the lack of time given to science on television (or radio, or newspapers for that matter). Most of the discussion on global warming comes from the Internet, mainly blogs written by people with extreme viewpoints on both sides. Either the whole thing is a “hoax” or we’re all going to die soon.
Dick Wexelblat from Merion Station, Pa. asked: “What does global warming mean for us in the NBC Philadelphia viewing area? Will sea level rise? If so, what does that mean for the shore, for Philly, etc.?”
The first thing is to establish that there indeed is a phenomenon called “global warming,” and that is at least partially due to increased carbon dioxide from the burning of fossil fuels. An overwhelming number of climate experts agree. In fact, the more a researcher publishes on the subject, the more likely he or she is to agree.
Think of this analogy: you are concerned about severe headaches and want to know what might be wrong. Won’t you want to go to a doctor who specializes in this -- a brain surgeon? Would you take the word of your regular doctor, or chiropractor, or a relative who’s a hypochondriac? There are plenty of scientists who are skeptics on global warming, but if they’re physicists, or oceanographers, or even meteorologists, why would we expect them to know more than the scientists all over the world who research (and publish) about this subject?
I sure wouldn’t want a biologist to tell me we’re going to get severe weather tomorrow! (No offense, biologists).
One of the main arguments from skeptics is that global temperatures are caused more by changes in the sun than human activity. But here’s the “smoking gun” on that: If it were mainly the sun, both the lower atmosphere (troposphere) and upper atmosphere (stratosphere) would warm. But that’s not happening. The troposphere is warming, but the stratosphere is COOLING! What would explain that? The greenhouse effect, where some of the warmth in the troposphere gets “trapped” by carbon dioxide and gets sent back down.
The other strong evidence of the threat of warming is in the Arctic. This is the scariest piece of evidence I’ve seen:
While graphs of global temperatures sometimes show subtle changes -- especially in the past 10 years -- this one is unmistakable. The trend is down -- pretty much straight down. There are changes from year-to-year, of course, but it’s hard to imagine anyone arguing about the trend with a straight face. Notice how the ice area dropped rapidly from 2004 to 2006. That scared a lot of people on the “alarmist” side, causing some to wonder if all the Arctic sea ice would be gone in a matter of a few years. Then, when it went back up in 2008, many skeptics started saying that the ice had recovered, and this was no longer a problem. That’s the problem with looking at a single year or group of years and drawing conclusions about climate. Averaging over a number of years shows a clear and steady trend downward.
Oh, and about the stories that the warming stopped during the first decade of the 21st century, take a look at this:
Looks like pretty widespread warming, especially in the northern latitudes, which is key to the future.
Now, the potential affects on our area…
Rising temperatures overall would likely lead to more hot summers and fewer cold winters later in the century. That doesn’t mean “no more cold, snowy winters.”
If ocean temperatures warm in the future, that would lead to more water vapor being available for storms. It wouldn’t necessarily mean more rainy days, but when we would get storms (especially with a flow off that warmer ocean), rains would tend to be heavier. Extreme rainfall/flood events would likely increase.
There is already evidence that this is happening. The graph below shows the percent of extreme one-day precipitation events for the U.S. over the past century. The upswing since 1990 is pretty obvious. We’re not talking about a couple of years here -- 20 years is a significant enough time to detect a trend:
This also has implications for snowfall. Warmer ocean temperatures nearby could lower the frequency of snowstorms, but the higher water vapor that comes with it would lead to higher snow totals in the few storms that do occur. Could this already be happening here? Is it a coincidence that five of the 12 biggest snowstorms in Philadelphia’s recorded history (more than 120 years) have fallen in the past EIGHT winters?
SEA LEVEL RISE/COASTAL FLOODING:
A warming ocean causes sea level to rise, even without melting ice. Add the melting from places like Greenland (already accelerating faster than computer models have suggested) and northern Canada, and the modest forecasts from the past 10 years would need to be revised upward-perhaps by a lot.
Ice melt is a classic “positive feedback.” Higher temperatures melt more ice. Since there would be less ice, more heat would be absorbed by the oceans, rather than be re-radiated back into space. That would raise ocean temperatures even more, which would lead to more ice melt, which leads to more ocean warming, then more ice melt…
This is how rapid climate change can occur, and has probably occurred in the past.
Here’s a nice site that shows in detail what the effects would be with sea level rises. Remember, one meter equals about 3.3 feet. There haven’t been many computer model forecasts of sea level rise more than one meter this century. But in future centuries, if the warming continues, higher sea level rises would be likely. What the graphic shows are the areas most vulnerable to sea level rise.
Let’s start up in Long Beach Island, N.J. (feel free to check out any area). A one-meter rise isn’t too threatening, except for Route 72, the only escape route from the island. It would have to be reconstructed in certain areas. Flooding at the ocean side would happen much more frequently than today, since we could add 3-plus feet to any flood that would occur nowadays.
Farther south, there would be similar problems in the Atlantic City/Ventnor/Margate/Longport area. Routes 30 and 40 (White Horse and Black Horse Pikes) would be underwater in places and have to be reconstructed. It would take much less of a storm to flood Bayside areas of Ventnor and Margate that flood easily today. Imagine having a three-foot head start!
We see similar problems as we go south, until The Wildwoods. What a difference! Numerous areas would be flooded even with a one-meter rise. Now look at two meters -- MOST of the area would be underwater -- WITHOUT EVEN A STORM! This area appears to be the most sensitive to sea level rise in our entire region.
Problems in Delaware appear to be mainly right at the ocean, with even weak storms leading to significant flooding.
Many towns along Delaware Bay would be in big trouble, too. And, by the way, check out the flooding at Philadelphia International Airport with just a one-meter rise!
THE BIG WILDCARD... THE EFFECT OF MELTING ICE ON THE GULF STREAM AND OVERALL WEATHER PATTERNS
Maybe we should re-label the phenomenon “Arctic Warming That is Screwing Up Weather Patterns Around the World.” OK, maybe a bit too wordy. But this is the main complication in the simple warming scenario. Our past two winters have featured highly unusual patterns that were most extreme in the Arctic and nearby areas. We’ve discussed this in past blogs.
Temperatures in parts of Greenland and Northeast Canada were close to 40 degrees above average in December! You might remember our very cold December. It was a mere 5 degrees below average. If we had the 40 degree anomaly, our high temperatures would have averaged 85 degrees…for EVERY day in December! Some days would have to be in the 90s to get an average that high. That’s impossible, isn’t it?
This shows just how extreme the weather can be in the Arctic. Recent studies have shown that the Arctic has warmed at twice the rate of the global average, which is just what computer models have been predicting for decades. Warm the Arctic and more ice melts, which would raise temperatures even more. What if this warming is altering weather patterns, leading to more high pressure near Greenland? That type of pattern has had a major role in the past two snowy, cold winters, not just around here, but in Northern Europe as well. More years of this pattern could lead to more cold, snowy winters if that theory is right. All while the earth is warming overall.
The other wildcard is the ocean circulation in the Atlantic. It’s called the Thermohaline Circulation, and it is quite complicated. But it is responsible for warmth spreading from the tropics toward the Eastern U.S. and Europe. Without that circulation, temperatures would be MUCH cooler. There are some scientists who speculate that increasing ice melt in the Arctic could put so much fresh water in the North Atlantic that it would interrupt the circulation and at the very least slow it down.
THE BOTTOM LINE:
The above section is just one of the reasons no prediction far in the future is a sure thing. But the overwhelming evidence -- not just computer models, as some suggest -- shows significant warming over the past century, and a likelihood of an acceleration of that warming in the next century, largely due to ice melt.
Our area would be more likely to see more hot summers, more frequent and severe flooding, and some permanent changes at the shore. But our area will survive. We will just have to adapt.