But, 'bad' is a relative term and encompasses a broad range, going from barely anything to making the world uninhabitable. What do we mean by 'bad'? There was a very interesting a well-written article that recently appeared in the magazine New York. The author, David Wallace-Wells, compared the effects of different temperatures increases, each of which is a possibility (albeit, diminishing), as compared to today's temperatures. Some of the topics discussed were:
- Trillions of tons of methane gas trapped in the tundra is now beginning to be released and is 86 times more potent as a greenhouse gas, per volume, than CO2;
- There is only a small chance that we will control our emissions enough to keep temperature rise to under 2 degrees Celsius;
- With only one exception, previous mass extinctions were caused by climate change and we are changing the climate at a much higher rate than seen in any of those events. Even the impact event that led to the extinction of the dinosaurs did so by changing the climate;
- The temperature is rising so high in some parts of the world that it is now dangerous, even deadly, to work for extended periods of time outside. Workers in some of the poorest regions are already exhibiting the effects of a slow heat death where you suffer cumulative effects over a period of time as opposed to a quick death from heat stroke or heat exhaustion;
- There has been a 50-fold increase in the number of places experiencing dangerous heat levels since 1980. The five hottest summers since the year 1500 have all occurred since 2002;
- Even if we meet the 2-degree target, many of the hottest places on Earth will become nearly uninhabitable. This number will, of course, increase as temperatures go even higher;
- Food supplies will decrease at the same time the world population increases. There are already large parts of the planet with malnourished populations - about 800 million people worldwide;
- Diseases will spread and there is a risk of deadly diseases which have been locked up in the polar ice of being released. While most of these diseases would not survive and don't present a risk, it is entirely possible some will and people have already died from diseases being released in this way;
- Air pollution will get even worse. Forecasts are that approximately 2 billion people will be breathing air polluted beyond the 'safe' level by 2090;
- 10,000 people are currently dying every day due to particulate air pollution, partly due to an increase in the wildfire season which has increased by 78 days since 1970;
- Increased temperatures lead to increases in violence, including crime and warfare;
- One Celsius degree of temperature increase costs the world economy 1.2 percent of the GDP. That would be $6.3 trillion per year, based on 2013 figures for the world's GDP;
- The rate of sea level rise will increase;
- Ocean acidification will devastate ocean populations, threatening this critical food supply.
This article painted a grim picture. But, how accurate was it?
Basically, the science in the article is accurate and the writer has his facts straight. I can personally attest to the effect of working in temperatures over 100 degrees Fahrenheit. It is brutal for even limited periods of time.
The other depictions of things as they are today are correct. But, that doesn't mean things will play out as a disaster. And, I don't mean to say the article paints a worst-case scenario, because it doesn't. Truthfully, it's a middle-of-the-road scenario. The extreme end is that we are doomed. One climate scientist, Dr. Guy McPherson, has been quoted as claiming the human race will be extinct by the year 2030. He maintains a blog on human extinction at Nature Bats Last. How likely is that scenario? In my opinion, practically zero. Just do the math.
The human population is currently (as of April 2017) about 7.5 billion. There are, currently, about 135 million births every year and around 56 million deaths, resulting in a net increase of about 79 million people per year. That's an increase of over 216,000 people every day.
Now, kill them all in the next 13 years. You would have to decrease the world population by an average in excess of 570 million people every year. That doesn't mean to kill off that many because we have to get rid of the extra 79 million we're adding. To reduce the world population by 570 million this year, we would have to kill about 650 million people. In case you're wondering, that's an average of about 1.8 million people every day. To put that into perspective, the Ebola epidemic caused worldwide panic. People were obsessed by the death toll and kept a running count. The total? 11,300 in 24 months. That's 470 people per month, fewer than 16 per day. To wipe us all out, we would need to kill 112,500 times that many every single day, day in and day out, for 13 years. I can't imagine a scenario where that could occur.
To put the size of the human population in perspective, imagine reducing the size of the population by 1 million people every single day. That is the size of a large city. It would still take over 20 years to kill us all at that rate.
So, I am not concerned with human extinction. However, that does not mean we won't see a lot of human misery. I feel it is highly likely we will see a point in the coming decades where the population begins to decrease. This is based on the fact that so many people are already dying as a result of climate change and the factors responsible for killing people are getting continuously worse. That means the death rate will increase from the current 150,000 people per day to greater than 370,000 people per day. And, that is to merely reach the zero population growth mark. It would have to increase even more to achieve negative population growth. If my estimate is correct, then we'll see a lot of people dying in the years to come.
The New York article also discusses the idea of limiting our emissions to avoid temperature increases of 2 degrees Celsius. It appears we have already passed that point. Two independent studies published in Nature Climate Change this past week have shown we have locked in temperature increases exceeding the 1.5 degree goal of the Paris Treaty. Here is a plain language article about these papers.
The first study (Less than 2◦ C warming by 2100 unlikely, by A.E. Raftery, et al.) used a country-by-country analysis to examine economic growth based on population predictions. They found there is a less than 5% chance that we can limit temperature increases to 2 degrees. The most likely increase, based on their analyses, is between 2 and 4.9 degrees with a median of 3.2 degrees.
The second study (Committed warming inferred from observations, by and