Understanding Climate Change

Lilac II
Creative Commons License photo credit: starmist1

I just wrote this rather long comment on Fern’s blog, in response to her post on climate change. I really love her blog and don’t mean to sound critical, but I thought it was worth repeating here, because her comments reflect a common misconception about how scientists are investigating climate change. Often people look at one year or one season’s weather and notice it is cooler than the previous year and so conclude that there isn’t clear evidence of climate change. The problem with this is that you can look at 1 or 2 years or even 3-5 years and find evidence for or against climate change.

There is a big difference between observing the weather and measuring the climate. I understand why many people, including some scientists are still not sure, but it’s important to talk about why so many scientists are convinced. Weather in individual places over time might be warmer or cooler year to year or season to season–there are always those types of variations. What makes many scientists worry is the changes in average temperatures world wide, over decades.

Biologists are also finding many plants and animals that are changing their ranges or flowering earlier. As gardeners, we can and should be helping to gather evidence about climate change in our local areas. Some gardeners regularly monitor the weather, including daily highs and lows, rainfall, and the first and last frosts of the year. This is the kind of information that, if it’s continuous for decades, lets you begin seeing climate change in action. You can also monitor your garden plants for changes in seasonality. If you want to monitor climate change for yourself and help scientists you could join the National Phenology Network. Their volunteers have been monitoring the dates of flower blooms (lilac and honeysuckle since 1956).  It’s normal to see flowers bloom earlier one year and later another, but when you monitor for decades and the average bloom date gets earlier and earlier, that’s when scientists start to worry.

It’s common for people to look at year to year variations and wonder where the evidence is, but a climate scientist is looking at decades (for temperature and precipitation changes) or centuries (if they are looking a CO2 levels in frozen ice.)

Here are a couple of audio stories from NPR about phenology.

Climate Scientists Enlist Citizen Volunteers
Beautiful Lilacs Tell a Tale About Climate

If you want more information, you might want to pick up The Weather Makers: How Man Is Changing the Climate and What It Means for Life on Earth by Tim Flannery. Flannery does a good job of explaining what evidence scientists are examining and related politics.

2 thoughts on “Understanding Climate Change

  1. Fern @ Life on the Balcony

    I appreciate your commentary and in no way am I offended or think you are being unnecessarily critical. I’m a lawyer by training, so your post is pretty tame compared to what I’m used to! 🙂

    There are a couple of things I think proponents of climate change/global warming rarely address when they are discussing their support of the theory, and I would be interested in hearing what you have to say about them: 1) The reliability of the long term data that we have, 2) the proof that any trends are related to human activity, and 3) the likelihood that any changes in human behavior now will be able to reverse any trends in climate change.

    I understand that looking at one year’s worth of data, or even a couple of years, isn’t enough to determine whether there is a long term trend. In my post I was trying to be lighthearted and avoid politicizing a container gardening blog. The primary point of the post that you are responding to was to say that people who are on the fence about global warming shouldn’t use their ambivalence about it to refrain from conservation and general environmental protection. I think the politicization of global warming has led to a backlash against the environment by centrist and right of center folks who viscerally respond to most of what the far left supports.

  2. Gardengrrrl

    You have some good questions. 1) The reliability of the data-There are various different aspects to reliability. In general the measurements of CO2 levels in the ice can be considered accurate because we can compare them to recent measurements of CO2 in the atmosphere to calibrate. Also, you can take ice cores multiple times or in different locations and see if they produce different measurements. The part that is less reliable is the modeling-that’s a lot of math that I don’t understand, but you can see from the chart in “An Inconvenient Truth” that the rate of CO2 rise varies considerably from model to model. Unfortunately, they all agree that the change is significant. 2) Is it human influence? Both climatologists and paleobiologists (who study ancient ecosystems) have strong evidence that there has never before been such a sudden, severe change in the climate/CO2 levels. By looking at many types of evidence you can get this type of picture. My friend studies pollen from ancient lake bottoms. When there is a change in the climate, the plants around the lake change and thousands of years later you can dig up the pollen and get a good idea of what changes happened. You can also study glacier ice and polar ice for CO2 levels. The climate on the earth does change naturally over time, but it does so slowly and in regular cycles. What is happening now is happening very fast in comparison to those types of changes. There are many different lines of evidence that point to humans. Also, the rise in CO2 just happens to start right after the start of the industrial revolution. All these things could be a coincidence or there could be some unknown factor that we haven’t found yet, but right now all the evidence points towards us. 3) What are the chances that we can change the trend now? Truthfully? Not great. Once there is excess CO2 in the atmosphere it may take a long time (hundreds or thousands of years) for levels to go back down. None of the climate change treaties go far enough in asking countries to reduce greenhouse gases to truly reverse things. The idea is to stabilize the levels so that the climate warms some, but we slow that process and allow temperatures to restabilize. If we don’t do anything then things will just get worse and natural systems will be less able to adapt. At scientific conferences I have been to in the last few years people had moved on from discussion of whether or not there is climate change to “how can we help people in vulnerable situations deal with climate change?”

    I’m not sure it is possible to talk about climate change without being political, but we can at least be polite and talk openly about it. There have been some ideas suggested for ways to get the CO2 out of the atmosphere, but doing this manually would be amazingly expensive. Conservation seems a much more reasonable response to me. We can hope that as CO2 levels rise plants will start to take in more CO2 and grow bigger, absorbing the excess, but so far the evidence of this is very mixed. The big worry is that at some point the change will be so rapid and severe that it will cause a major shift (a turning point) such that there is a large plant or ocean algae die-off, or the major ocean currents are affected. I hope that day never comes.

    On a hopeful note, as gardeners we can help by conserving and monitoring the weather, plant growth, and other seasonal changes long term. Careful observation and recording is what scientists do and it makes for good gardening as well. For example, you may find out that the microclimate in your garden allows you to plant earlier than gardening books say. Watching all those details and recording them in my garden journal is one of my favorite things about gardening. I feel like I know secrets that other people don’t. 🙂

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