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How Big of an Issue IS Climate Change?

All semester long you have been encouraged to look at the WEIGHT of evidence for or against a particular idea, to weigh that evidence logically, then make your own informed choices and decisions. Climate change is a great concluding topic for the semester, because to understand it you must bring together all of the skills you have learned.

Climate change is the single greatest challenge we face today, both as a society and as a species. It has had significant, measurable social impacts already, and will have even greater impacts in the next 50 years. Regardless of whether human society chooses to continue ignoring it, or we take aggressive steps to limit it, climate change will force us to make tough choices that impact every aspect of our daily lives.

At the same time, climate change is widely misunderstood. Bring up the topic in conversation, and almost immediately the group splits at least 3 ways: those who dismiss it as a political hoax, those who are certain life is coming to an end, and those who are worried but cannot tell you why.

In exploring this topic you will learn what we can say with confidence about climate change, and why. You also will see why we have more confidence in some predictions, and less in others.

How are climate predictions made?

Climate changes are predicted using grid models: systems of differential equations based on the laws of physics, fluid motion, and chemistry. In a grid model, the surface of the Earth is divided into a grid. For each square of the grid, there is a stack of cubes extending down below the surface of the land or water and up into the atmosphere. Each cube has preset properties and rates of exchange of heat, moisture, etc. As a grid model runs it calculates winds, heat transfer, radiation, relative humidity, and surface water actions within each cube. Then it calculates how the results for one cube affected the neighboring cubes.

Grid models are some of the most complex computer systems ever developed (and they continue to improve), but they cannot account for every possible variable. Also, there are different ways to handle the same variables. Climate scientists allow for these differences by using three different grid models:

Data from the models as well as the underlying computer code are available to all scientists and to the public. You can see it for yourself at the links listed above.

The three different grid models make predictions independently of each other. If all three models make the same prediction, climate scientists are more confident that the predictions closely approximate what is likely to happen.

A basic grid model

Schematic of a climate "grid" model. The surface of the Earth is divided into a grid. Each horizontal grid square has a vertical stack of cubes extending into the ground or water, and up into the atmosphere. The equations model changes in each cube individually, then effects of each cube on its nearest neighbors.

Grid models are tested against field observations

Modeling is only part of the story. Model predictions must be tested against reality by going into the field and looking for evidence to support or refute the predictions. If the predictions of early changes in climate made by models are supported by observations from the field, climate scientists have greater confidence in that model's long term predictions. If the predictions are not supported by observations in the real world, then the model's predictions are unreliable.

The process of building and running models, testing their predictions against observed reality, and refining the models, has been going on for many years. As a result, the models are considered extremely reliable and accurate.

What do scientists AGREE on?

An estimated 97% of the scientific community agrees with these summary statements.

  • Climate change is real. It is not a random fluctuation but a directional overall warming of the entire planet by an average of 1.6oC since 1900.
  • There is overwhelming evidence that these changes are a direct result of human activities. There is insufficient evidence to support any other possible cause.
    • It has been happening for several thousand years, and has accelerated since the start of the Industrial Revolution.
    • Never before in the history of Earth has the climate shifted so rapidly.
  • Climate change will both continue and accelerate as long as the underlying causes remain in place.

These statements are based on data from climate grid models, field observations of current conditions, and data from paleontologists about the Earth's past climate history.

What does the scientific community DISAGREE about?

There are four main points of disagreement. None of these contradict the basic accepted statements of fact listed above.

The RATE at which disruptive climate change will occur.
We know that disruptive changes will occur within decades, not centuries. However, we cannot say with confidence whether we will see continued slow change, or reach a "tipping point" after which there will be sudden runaway climate instability.

How much climate change will be in SPECIFIC locations.
Current climate models can predict changes with high confidence on a global scale, and are increasingly able to make predictions on a continent-wide scale. For instance, climate modelers now can predict with confidence which parts of North America will be drier or wetter as the climate warms. However, predicting the effects of climate change on one particular location (say, one city) is not within their abilities just yet.

How RESILIENT natural ecosystems and human society will be.
How much climate change can we adapt to successfully? At what point will ecosystems stop adapting and collapse instead? Which human systems and networks will fail first, and so have greatest need of our attention?

How best to RESPOND to climate change.
Some scientists think the best strategy is to attack the main drivers of climate change (which you will learn about from the reading). Others recommend making social and political policy changes that will help us limit our impact, and adapt as a society to climate changes that have already happened. Still others believe intervention is futile, and runaway change is inevitable; they focus on finding new ways to produce food, water, and energy within the context of a warmer global climate.

So Why Is There Still Any Debate? Why Are We Not Acting?

If the scientific community accepts climate change, why does the general public still doubt it? More important perhaps, why are policymakers so resistant to taking action?

Reason 1: How Science Is Perceived vs. How It Works

Non-scientists tend to think of science as a body of well-defined facts that have been tested and proven beyond all doubt. Yet as you have learned, evidence and data collected through the process of scientific investigation is open to reinterpretation based on new findings. One experiment or observation is not enough; the scientific community only accepts conclusions that are based on multiple independent pieces of evidence.

The scientific community also rarely uses the word "certain." Instead, scientists speak in terms of "confidence" and "likelihood." For a scientist, even the sunrise tomorrow is not certain. Instead they might say, "given past behavior of the sun, there is an extremely high likelihood it will rise tomorrow." They might add, "I have a high level of confidence in my observations, because I have seen this every day for the last 30 years. My colleagues across the world have consistently reported similar observations."

This example sounds silly, but it is how modern science works. Unfortunately, scientists' resistance to saying they are certain plays a role in the second reason we continue to debate climate change rather than move forward towards solving it.

Reason 2: How Climate Change Has Been Reported

Looking at the overall body and weight of evidence for or against a particular idea is a core principle of science. Unfortunately it conflicts with a fundamental principle of journalism: "fair and balanced reporting." A "fair" journalist is obligated to give equal time to all sides of a story. Balanced reporting makes it harder to educate the public about issues like climate change, because giving equal time to both sides of the story suggests there is still debate or uncertainty in the scientific community. As you just read above, that is a myth.

Reason 3: Socio-Economic Inertia

If climate change is the result of human activities, it follows that mitigating climate change will require changing human behavior. It will require changing both long-standing economic models and social customs and practices.

Economic change is extremely difficult, if for no other reason than our global economy is based on fossil fuels. The world-wide infrastructure dedicated to a fossil fuel-based economic model took more than a century to develop; switching to a non-fossil fuel-based economy is likely to take decades, and will be very expensive. On the other hand, responding effectively to climate change will create new economic opportunities and markets for innovation that have not existed before.

Social change will be just as difficult. Americans have grown accustomed to a consumption-intensive lifestyle. This is reflected in our carbon "footprint." While US citizens make up ~5% of the total world population, they are responsible for ~26% of greenhouse gas emissions worldwide. This is not a uniquely American phenomenon. As the US standard of living is adopted by other countries, their respective national carbon footprints grow as well. Inevitably citizens of the US and other developed nations will face tough choices about their personal lifestyles in the near future. If they choose not to make adjustments on their own, global climate change will force change.

Reason 4: The Size of the Problem

The sheer size of the problem makes it seem impossible to solve. Addressing global climate change requires thinking on a global scale. No single country can solve it; there MUST be an international effort. At the same time, there will not be a single uniform solution. The overall problem will be solved by addressing many smaller issues at the same time.

Consider the problem this way: you are driving in Africa, and come to a dead elephant blocking the road. There is no way to get around it; you HAVE to move the elephant, all 13,000 pounds of it. Our immediate response usually would be to give up.

This does not mean the problem cannot be solved though. Imagine we change the problem slightly, so that this time the road is blocked by a pile of 375 grey cinder blocks, each weighing 35 lbs. The total weight blocking the road is the same (13,000 lbs.) Yet by moving 3 blocks a minute, one person could clear the road in about 2 hours. The point is that the perception of the size of the problem is hampering smaller meaningful steps that when taken together provide a solution.


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Page last modified on Wednesday 13 of April, 2016 19:24:25 EDT

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