Food for Thought on a Hot Summer's Day

This year, the concentration of CO2 in our atmosphere exceeded 400 parts per million (ppm) for the first time in about 2.5 million years.  So right now, CO2 makes up about 4/100 of a percent of our atmosphere.

Big deal, you might say.

Well, consider this, if we had no CO2 in our atmosphere, the Earth would be a frozen from pole to equator. Even though our planet is in what astronomers and planetary geologists call the “Habitable” or “Goldilocks” zone, where the amount of sunlight is not too much or not too little, it is at the outer edge of that zone. Without CO2, the average temperature our planet would be more like Mars.

It is clear to most earth and atmospheric researchers that CO2 is a driver of climate. This is because CO2 absorbs infrared radiation which occurs when sunlight hits the Earth’s surface. The surface warms and re-radiates the energy as infrared. The infrared radiation cannot escape to space because of CO2 and thus warms the atmosphere. This property of CO2 has been known for almost two centuries, which is a long time from a human perspective.

Also consider this, for the past 2.5 million years, the climate has been very unstable, shifting between extremely cold and a climate much like todays until about 10,000 years ago. At least four times during the last 2.5 million years, the Earth has flipped between ice age and interglacial climates, like the one we live in now.

It has made these changes very rapidly from a geologic perspective. For example, 100 ppm increase in CO2 from the depths of the last ice age to our current climate only took about 7,000 years. That’s the difference between one mile of ice where you sit right now and our sunny humid weather on July 14th, 2013, a blink of an eye in terms of the Earth’s 4.55 billion year history.

Now consider this, the change from 270 ppm in the early 1800s to 400 ppm this year took a bit over 200 years. That’s 35 times faster.

Also, modern civilization started and advanced during the 10,000 years climate has been relatively stable, that is, stable from our point of view.

So why should we care? What does CO2 have to do with ice ages anyway?

The glaciations are caused by a confluence of several factors. Glaciologists and climatologists have determined that our current glacial climates can be explained by changes in Earth’s orbit around the sun, the tilt of the Earth’s axis, the ocean ocean’s currents and position of the continents and last but not least, the amount of CO2 in the atmosphere.

So why have we been in this unstable climate condition?

First, CO2 in our atmosphere has been steadily decreasing from a high of about 1,200 ppm about 45 million years ago to 230 ppm when the first glaciation started and CO2 concentrations plummeted much lower. When CO2 decreases the Earth gets colder. When shifting of the continents lead to the creation of the Panama isthmus, the last low- latitude direct connection between the Pacific and Atlantic closed, so warm waters could not circulate between the two oceans except at extreme southern latitudes around Antarctica. This change allowed the cyclic changes in Earth’s orbit and tilt to have stronger effects on our climate.

Again, so what?

Well, as the Earth cools, so do the oceans. Cold water can hold onto dissolved gases better than warm water. So as the climate starts to cool the oceans absorb CO2 and this accelerates the cooling. In a matter of a few thousand years, ice starts building up on the oceans and continents. As shifts in Earth’s orbit and tilt allow more warming by the sun, that CO2 comes out of solution in the oceans and accelerates the warming of the air, so the glaciers melt, sea levels rise.

OK, so you keep asking – what’s my point?

My point is that we, by rapidly increasing CO2 in the atmosphere, are driving the climate. To where we are driving it is the question.

The last time the Earth’s atmosphere had CO2 at 1000 ppm; the Earth had no ice at the poles. Sea levels were hundreds of feet higher than they are now. Fossils of crocodiles and palm trees north of the Arctic Circle from that time period are common.

If tropic climates existed in the Arctic back then, what does that say about what the climate was in our current temperate zones, let alone the tropics? The evidence says that those areas would have been uninhabitable by today’s standards.

The evidence is unequivocal that the accelerating increase in CO2 since the dawn of the industrial age has been caused by us. The good thing is we have probably postponed the beginning of the next ice age. By how much, who knows? The bad thing is that at the rate we are putting CO2 into the atmosphere; the concentration will reach about 1000 ppm sometime around the end of the century, maybe sooner.

I am not saying that by 2100, our coasts are going to drown and palm trees will be growing in Fairbanks but if the trends continue, that could be the case a few centuries down the line.  

I am saying we are in the process of forcing the climate to shift in ways we cannot anticipate exactly but in ways the geologic record says will be very unpleasant for future generations. Maybe not our children, but probably their children and subsequent generations.

That’s my point.

So what do we do about it?

I was chided by a commenter a few months back after I wrote a post on Hurricane Sandy and its relation to climate change because he thought I wanted us to abandon fossil fuel use right now and go back to our agrarian society where we used horse and buggy.

Actually, I made no such suggestion.

What we do need to do is get away from fossil fuels, but can we get away from them?

Maybe.

That’s no easy task because fuel sources as energy dense as coal, petroleum and natural gas that fuel our modern society just do not exist.

Our centralized electric energy distribution infrastructure is based around fossil fuels so cannot accommodate solar or wind easily. Changing the grid is going to cost hundreds of billion dollars and it won’t happen any time soon, according to latest reports.

The biggest bang for our buck is to start using less energy and that is not all that hard to do.  As people replace appliances and cars, newer ones are more efficient.

The oil burner I installed in 2006 is far more efficient than the 1985 model it replaced.

The small SUV I bought in 2005 got 25 miles a gallon and it replaced a minivan that got 19 miles a gallon. I replaced the 2005 this year with a small SUV that gets 30 miles a gallon (and the 2013 is bigger than the 2005). New mileage standards mean my next car will probably get closer to 40 mpg.

Efficiency by itself will not be enough. The price of solar energy is coming down. I was an early adopter of solar in 2008 and it has cut my electric bill by more than 60 percent. Granted my payback is going to take a long time as the price of electricity has leveled off due to the increased availability of natural gas but someone installing solar today is going to get their money back much faster because it is now cheaper.

But that won’t be enough either.

Nuclear will be needed. Today’s reactors are old technology, and the Fukushima disaster shows that this technology has its drawbacks. Newer technologies, such as Thorium reactors are considered safer. Nuclear waste is still an issue, but when you compare nuclear to coal, nuclear is still a far better option in my mind.

Anyway you look at it though, moving away from fossil fuels is going to be very expensive but so is doing nothing.

Dealing with the costs of climate change is going to be very expensive as well. The Department of Defense is already starting long range planning to deal with population dislocation, famines and conflicts which will be the result of climate change. Major coastal cities, including New York and yes, Boston are starting to plan for increased sea levels.

The first decade of the 21st century was the hottest on record. 2010 was the hottest year in the US. The average temperature in eastern Massachusetts has gone up 2 degrees C since the end of the 1800s. Growing seasons are changing and moving northward. We are seeing warm water fish in the oceans around New England which are usually found in the mid-Atlantic states. Wild fires and the amount of damage they do have increased substantially since the 1950s. The Arctic ice pack has decreased by 51% over the annual mean of the last two decades of the twentieth century. These observations are not alarmist exaggerations - they are facts anyone can look up with ease.

Let me leave you with this: Earth’s history shows that its climate has always been variable. It has always changed and it always will; however, the geologic record also tells us that several of the major extinction events of the last half billion years are associated with rapid changes in climate which occurred along with rapid changes in CO2. Given the rate that we are putting CO2 into the atmosphere, this trend scares the hell out of a lot of earth scientists. As a former earth scientist, it scares the hell out of me too.

The changes that are coming to our current climate are almost solely due to our actions whether we like it or not or believe in it or not.

Food for thought on a warm summer day.