Is Global Warming Anthropogenic?

Global warming is one of the most controversial issues in science today. Public opinion remains divided as to the exact role of humans regarding climate change, with 48% of Americans believing global warming is exaggerated.[1] Although many arguments have been put forward to diminish anthropogenic global warming,  some of the most commonly cited issues include: the perceived lack of scientific consensus regarding climate change; the argument that anthropogenic global warming is not, in itself, bad; that global warming results from solar activity, not human interference; and that the climate has always changed, and so current changes do not necessarily result from human activity.

Figure 1. Carbon dioxide levels and temperature from 450,000 BP.[2]

Whilst it is true that the climate has constantly changed throughout history, this does not necessarily negate the argument that global warming is anthropogenic. Figure 1 shows us that carbon dioxide levels and temperature certainly have been higher in the past compared to present-day, and this has been used to suggest that anthropogenic global warming is a myth, otherwise we would not have seen high temperatures and abundances of carbon dioxide prior to industrialisation. However, this argument could be countered scientifically, because the climate simply responds to factors that cause it to change – the prevailing factor in modern times being human activity. In the past, the temperature has risen for varying reasons. Periods of warming following ice ages (including the last ice age, which ended 10,000 years ago and is evident in Figure 1) have lead to increased global warming, alongside changes in the Earth’s surface (the most notable of which, the Palaeocene-Eocene Thermal Maximum, occurred 55 million years ago and is widely associated with global warming).[3] Therefore, whilst there has always been climate change, there have been significant past events that have caused it, and it does not necessarily negate the role of humans in present-day global warming.

It also frequently argued that, rather than being anthropogenic, global warming is caused by solar activity. This is because, in the past, there have been periods where solar irradiance and climate change have positively correlated.

Figure 2. Global temperature and total solar irradiance.[4]

However, as Figure 2 shows, solar activity has declined since 1980, whereas temperature has increased steadily since 1950, suggesting that there is no correlation between solar irradiance and global warming at all. Therefore, the argument that solar activity, rather than humans, causes global warming can be countered scientifically by looking at statistical information regarding solar irradiance and temperature change.

Furthermore, one of the primary arguments made against anthropological climate change is that the positive repercussions of global warming far outweigh then negative repercussions. The evidence presented for this focuses on the harsh climate that the Dark Ages and similar time periods faced, in which disease and frost was rife. It is often thought that countries at higher latitudes will benefit from global warming, namely countries within the Arctic circle, such as Canada and areas such as Siberia, who would seemingly benefit from having a warmer climate. However, this could be countered scientifically by explaining that such areas often have poor soil quality (and, hence would not necessarily benefit from warmer conditions).[5] Moreover, the melting of polar ice caps that results from global warming results in the loss of many habitats for organisms the world over, and so would not have positive consequences for the environment.

Lack of scientific consensus regarding global warming is also frequently given as a reason for believing global warming is not anthropogenic. The Global Warming Petition Project boasts over 31,000 signatures from American scientists, all of whom believe that there is insufficient evidence to conclude that climate change is caused by human activity. However, of the 31,000 signatures, a mere 39 are climatologists (0.13%),[6] suggesting that while there may be some lack of consensus regarding anthropogenic global warming, it would seem there is very little among scientists whose area of expertise concerns climate change.

It is difficult for scientists to prevent skepticism regarding anthropogenic global warming as they are unable to prevent media coverage which diminishes or denies the role of humans in climate change. However, as scientists have an increasing wealth of statistical evidence to support anthropogenic global warming, it is my opinion that facts will eventually outweigh fiction.

References

1. Goldenberg, S. (2010). Nearly half of Americans believe climate change threat is exaggerated. Available: http://www.guardian.co.uk/environment/2010/mar/11/americans-climate-change-threat. Last accessed 24th September 2012.

2. Gore, A (2006). An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It. New York City: Rodale Press.

3. Natural History Museum. (2012). What Causes Climate Change?. Available: http://www.nhm.ac.uk/nature-online/environmental-change/what-is-climate-change/climate-change-causes/index.html. Last accessed 24th September 2012.

4. Skeptical Science. (2011). Solar activity & climate: is the sun causing global warming?. Available: http://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm. Last accessed 24th September 2012.

5. Skeptical Science. (2010). Positives and Negatives of Global Warming. Available: http://www.skepticalscience.com/global-warming-positives-negatives.htm. Last accessed 24th September 2012.

6. Global Warming Petition Project. (2012). Qualifications of Signers. Available: http://www.petitionproject.org/qualifications_of_signers.php. Last accessed 24th September 2012.

Iguanas: Occupying Niches; or, Gratuitous Pictures of Lizards

As a child I absolutely adored lizards. Over the last couple of years, my love for lizards has re-emerged with a vengeance, a passion which was nourished a year ago when we acquired a (then) six month old bearded dragon named Mushu.

Recently, our mini-zoo expanded further with the addition of a five month old crested gecko. He – or, at least we think it’s a ‘he’ (it’s notoriously tricky to sex juvenile lizards) – is one of the most fascinating creatures I have ever encountered. He has the ability to move faster than my eyes can adequately track, and has the softest skin I have ever felt.

In addition, the bones in the feet of crested geckos are so small you can barely feel them when handling one. It gives the feeling that you are holding something almost as light as air, in spite of them utilising the setae (very small hair-like structures) on their toes in order to cling to your skin.

This ever-growing love of all things Lacertilia lead me to think back to a particular holiday I had as a child in Florida – a place that happens to be crawling with reptiles. There was one particular type of lizard I remember seeing all over the hotel gardens, which I, retrospectively, believed to be the iguana. They were green, had long claws, striped tails and possessed dewlaps. Having seen captive iguanas, these wild lizards seemed to be a lot smaller than their caged counterparts, however, I had attributed this to their proximity to humans (a consequence of which may have been that they did not live as long and, hence, were small).

However, when researching lizards native to Florida, I was saddened to learn that the iguana was not one of them, and began to doubt the accuracy of my memory (I was eight at the time!). Perhaps it was not iguanas that I had seen. Many different species of gecko and skink are native to Florida, but the iguana is not. In fact, the iguana is not native to any part of the United States.

But I was not wrong. Whilst not native to Florida, iguanas certainly do live there. It seems unwanted and escaped pet iguanas have now firmly established themselves in the Florida Keys, largely due to the subtropical climate of the Keys, as well as widely available vegetation. Insufficient predation has enabled their population to grow rapidly, and they are increasingly getting a reputation as a nuisance species due to their fondness of defecating in private pools! A fact probably made all the more infuriating by the iguana’s tendency to carry Salmonella bacteria.

Subsequently, many local residents are resorting to desperate measures to keep the iguana population in check, which varies from using iguana repellent to eating the iguanas!

The invasive species hit the headlines in 2010, when many brumating iguanas fell from the trees simultaneously as Florida temperatures dropped to record lows. Iguanas are one of many lizard species that brumate, along with my own bearded dragon. Brumation is akin to a ‘mild hibernation’, whereby the reptile will become more dormant in colder temperatures, with their metabolic processes slowing down, however, unlike in hibernation, they do not cease eating completely and they do not sleep through the entirety of their brumation. The cold weather had slowed their blood stream, causing these reptiles to stop gripping the tree branches as efficiently, and to fall, only to wake up several hours later and terrify local residents, who assumed they were dead!

Save the Earth?

It is (or I certainly hope it is) evident to the masses that the Earth is vital for humanity. We walk on it, we inhabit it, we drink its water and we eat its vegetation.

In spite of this, anti-environmentalist groups, like this one, still exist. They argue that environmentalists peddle ‘junk philosophy’ which puts the needs of the Earth over and above the needs and comfort of human beings (something which, evidently, they believe to be undesirable).

The general argument many anti-environmentalists have is that the Earth is 4.54 billion years old, which demonstrates how hardy the Earth is, and its ability to withstand billions of years of abuse and defilement. Therefore, instead of pointing to the Earth’s depleting resources as cause for concern, they point to the environmentalists themselves as the issue. The particularly paranoid video below from a group called Free Market America (their contribution to Earth Day) insinuates that the true agenda of environmentalists is to hinder the progression of America, and any attempt to conserve the environment, rather than being helpful, is actually damaging to the economy.

Those of us with our faculties intact will, hopefully, recognise this instantly for the Republican propaganda hokum that it is. Sadly, they may indeed have a point…

Whilst it is not my intention to play devil’s advocate, I can’t help but argue that if your reasons for wanting to save the Earth are solely for the continued survival of mankind, these guys may be right.

Humanity, save for water and a habitat, gains nothing from being eco-friendly. It’s time consuming, often expensive and we grow our food in laboratories now anyway.

In addition, there are so many threats to the existence of humanity that extend beyond the Earth, such as bioterrorism and nuclear warfare, that one could argue omnicide poses a far more imminent threat than global warming. Therefore, if we are simply going to kill ourselves, why not guzzle oil, drive 4x4s and leave the light on until then?

The truth is that there are so many more worthy reasons to save the Earth other than humanity.
The Earth consists of an estimated 10-30 million species – only 1.4 million of which we are aware of, and only one of which is the Homo sapien. It would be difficult to argue in favour of saving the Earth without explaining a bit more about its incredible inhabitants. Some of my personal favourites include:

1. The axolotl (Ambystoma mexicanum). This salamander is known for the amazing ability of being able to regenerate its limbs, which has lead to it becoming a species of great interest in scientific research. In rare cases, they have even been known to not only repair a damaged appendage, but also regenerate an extra one, much like the mythological Lernaean Hydra. Pollution and urbanisation have lead to the axolotl becoming Critically Endangered in the wild.

2. The mosquito (the Culicidae family). I find these guys particularly fascinating, not for any morphological reason, but because of the massive amount of devastation they have caused. Despite its diminutive stature, the mosquito boasts the title of the deadliest animal in the world. Mosquitoes are known to carry parasites and viruses to animals. The most famous of these – Plasmodium (malaria) was responsible for the deaths of approximately 1.24 million people in 2010 alone.

3. The Venus Flytrap (Dionaea muscipula). This carnivorous plant traps its prey when its trichomes are stimulated. After this, the Venus Flytrap releases enzymes which begin to digest its prey. Although popular as cultivated plants, I was surprised to learn that the Venus Flytrap is listed as vulnerable.

4. The aye-aye (Daubentonia madagascariensis). This lemur is exceptionally interesting in the field of evolutionary biology due to it being the only member of the Daubentonia genus and Daubentoniidae family. It is, perhaps, most known for its bizarre extended middle finger which it uses for foraging. The aye-aye’s unusual appearance has lead to it becoming a prime target for superstition in its native Madagascar, where a sighting is thought of as a premonition of death. Subsequently, many aye-ayes are killed on sight, resulting in it having a Near Threatened status – something certainly not helped by increasing deforestation.

5. The little brown myotis (Myotis lucifugus). I’ll let Sir David Attenborough do the talking about these extremely deviant critters:

It is not only the large variety of species that make the world such an interesting place. It is a place of grandiose natural phenomena. The Seven Natural Wonders of the World are a testament to that, all of which have formed without the aid of man.

So, if we can’t save the Earth for our own sake, it is important to consider what remains of the world without us. The Earth is full of diversity and unsolved mystery, and if that’s not reason enough to save the planet, I’m not sure what is.