How do I answer to global warming skeptics?

Question

I've been asked to do a presentation in school about the effects of global warming, and some skeptics always ask me the following:

1) Earth's climate has been hotter in the past then it is now or any future projections, so why should we worry?

2) All this could be natural, what makes you think it is caused by humans?

3) Isn't global warming good? We'll see warmer temperatures, and crop yields will increase

I need to give a response to these questions, so please help. Thanks a lot =)

Answer 1

This is a very comprehensive guide on what to answer to the skeptic's arguments. http://gristmill.grist.org/skeptics
and here's another good source: http://www.royalsoc.ac.uk/page.asp?id=6229

Some additional notes to your first point:
In the past we weren't 6.5 billion people on earth and we are already today living beyond our earth's assets. That is, we're using up many natural resources (not only oil) in a faster speed than earth can reproduce it. With global warming the total resources on earth will shrink. (Crop yields are expected to increase only in some northern areas and only up to a "relatively small" increase in temperatures which we are likely to reach even if we take significant actions to address global warming.)

To support your note 1 and 3 I find this link particularly useful: http://gristmill.grist.org/story/2007/1/9/131657/6469

Good Luck!

Edit:
Comments to the post above mine from louy lefty:
Yes, there are some exaggerations or simplifications in Al Gore's movie and I don't think it's the best movie to use to teach about climate change. However, this does not change the scientific facts also expressed by the judge that climate change is real:

"Despite finding nine significant errors the judge said many of the claims made by the film were fully backed up by the weight of science. He identified “four main scientific hypotheses, each of which is very well supported by research published in respected, peer-reviewed journals and accords with the latest conclusions of the IPCC”.

In particular, he agreed with the main thrust of Mr Gore’s arguments: “That climate change is mainly attributable to man-made emissions of carbon dioxide, methane and nitrous oxide (‘greenhouse gases’)."

(A quote from the link from louy lefty above)

Answer 2

<< 1) Earth's climate has been hotter in the past then it is now or any future projections, so why should we worry? >>

Skeptics often mention this but very rarely do they mention the timescales involved or anything that indicates they have any comprehension of the sceince behind global warming.

The planet has been warmer in the past but that was millions of years ago before humans existed. At that time life on earth was very different to how it is now, the whole ecosystems were different, the atmosphere was different. In fact, it could well have been a different planet altogether.

The Earth always has and always will, warm and cool of it's own accord. This is the result of a complex series of interactive cycles within the solar system. These cycles acts as the triggers for warming and cooling processes and amongst other things give rise to the coming and going of ice ages - an event which has a cycle of approx 125 million years.

The key difference now is that temps are rising many times faster than natural cycles can possible account for and faster than has ever before been known.


<< 2) All this could be natural, what makes you think it is caused by humans? >>

Scientists have known for over 100 years that humans are contributing to global warming (Svante Arrhennius, 1896). It's not a new concept and is one that has been studied in acute detail by generations of scentists from all disciplines and all around the world. Thi multi-faceted approach consistently draws the same conclusion - we (humans) are the primary cause of the current global warming and climate chnage trends.

It would be ridiculous and extremely ignorant to claim that we are not affecting the climate. We know, and have known for a long time, how the variuous greenhouse gases work.

Some gases are explosive, some poisonous, some lighter than air, some reflect heat, some absorb heat. It's these ones that absorb heat* that we term the greenhouse gases and the more of them there are in the atmosphere the more heat is absorbed.


<< 3) Isn't global warming good? We'll see warmer temperatures, and crop yields will increase >>

Yes indeed, global warming does have some benefits but for every benefit there is a corresponsing and more serious detirment.

Whilst some crop yileds will increase there are other and more crops that will perish. We're already seeing this, more so in Africa and Asia where any crop failure can have devastating consequences. As a rough rule of thumb a 1°C rise in temps leads to a net reduction in global crop yields of 10%.

Warmer temperatures can also be beneficial, especially to people living in the colder climate zones where rising temps have seen a corresponding fall in the number of cold related deaths and medical conditions. Conversely however, there has been a greater increase in the number of heat related deaths and medical conditions. Largely because it's a lot easier to warm yourself up in a cold climate than it is to cool down in a hot one.


* Saying they 'absorb' heat an over simplification of the more complex physical and chemical properties of the greenhouse gases but it's effectively what they do.

Answer 3

1) Earth's climate has been hotter in the past then it is now or any future projections, so why should we worry?

A. If you look at the charts, there are many natural heating and cooling periods. However, the latest warming is three times more than anything we've ever had on record. Plus, there are people that pull up a big chunk of ice from the arctics, they see the amount of co2 bubbles in the ice. Even though the amount has gone down drastically since the clean air act was passed, they are still much higher than years before.

2) All this could be natural, what makes you think it is caused by humans?

A. See above.

3) Isn't global warming good? We'll see warmer temperatures, and crop yields will increase

A. If you think the global ice caps melting, causing tsunamis and 20% of the land worldwide under water, including Tokyo and San Francisco, then yeah Global Warming is amazing. Otherwise, it kinda sucks.

Answer 4

1) The Earth's climate has not been hotter for thousands of years. All the species on Earth right now are adapted to the current climate, not a much hotter climate.

2) It's very complicated and impossible to prove with 100% certainty, but I'll provide the basics of the evidence that's convinced almost all climate scientists that humans are the primary cause of the current global warming.

Basically we know it's warming, and we've measured how much:

http://www.ncdc.noaa.gov/img/climate/research/2005/ann/global-blended-temp-pg.gif

Scientists have a good idea how the Sun and the Earth's natural cycles and volcanoes and all those natural effects change the global climate, so they've gone back and checked to see if they could be responsible for the current global warming. What they found is:

Over the past 30 years, all solar effects on the global climate have been in the direction of (slight) cooling, not warming. This is during a very rapid period of global warming.

http://news.bbc.co.uk/2/hi/uk_news/6290228.stm
http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf

So the Sun certainly isn't a large factor in the current warming. They've also looked at natural cycles, and found that we should be in the middle of a cooling period right now.

"An often-cited 1980 study by Imbrie and Imbrie determined that 'Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6,000 years ago will continue for the next 23,000 years.'"

http://en.wikipedia.org/wiki/Milankovich_cycle

So it's definitely not the Earth's natural cycles. They looked at volcanoes, and found that

a) volcanoes cause more global cooling than warming, because the particles they emit block sunlight

b) humans emit over 100 times more CO2 than volcanoes annually

http://www.gaspig.com/volcano.htm

So it's certainly not due to volcanoes. Then they looked at human greenhouse gas emissions. We know how much atmospheric CO2 concentrations have increased over the past 50 years:

http://en.wikipedia.org/wiki/Image:Mauna_Loa_Carbon_Dioxide.png

And we know from isotope ratios that this increase is due entirely to human emissions from burning fossil fuels. We know how much of a greenhouse effect these gases like carbon dioxide have, and the increase we've seen is enough to have caused almost all of the warming we've seen over the past 30 years (about 80-90%). You can see a model of the various factors over the past century here:

http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

This is enough evidence to convince almost all climate scientists that humans are the primary cause of the current global warming.

3) No, there's a point at which more warming is not good. If warming were always good, then we might as well just move to the Sun.

Answer 5

1) we should worry because in the past tempreature extremes have led to the extinction of many species. Previous heat rises have led to ice ages, and even if humans can survive thanks to technology, there will be no plant or animal life for us to eat

2) first of all even if it is natural, that doesn't mean global warming is not occuring so we still have to be worried about what the effects are. Secondly, (and here is where you need research) many many studies have found evidence of links to human actions

3) global warming will drown island nations, increase the frequency and intensity of hurricanes, droughts, flooding and it is getting warmer faster than plants/ animals can adapt to it so it may lead to increased crop yield for *maybe* 10 years, but then it will be very hard to grow anything

Answer 6

you're never going to convince international warming skeptics of something because they prefer to be skeptics. Over ninety% of scientists are confident that the overall public of the present international warming has been brought about by utilizing human beings. If it is not any longer sufficient to convince you, then you're probable no longer keen to be confident. I only favor to address 2 misunderstandings that were repeated in this talk. a million) "organic cycles". certain, there have been organic cooling and warming cycles over the Earth's historic previous. Does that mean that human beings won't be able to strengthen those temperature alterations or reason our own? for sure no longer. in case you analyze the organic cycles you'll keep in mind that they don't replace as a lot or as quickly certainly because the present international warming. as well, the cooling and warming interior the twentieth and early twenty first centuries were very appropriately modelled by utilizing a blend of human and organic outcomes. for instance, cooling interior the 70s replaced into brought about by utilizing particulates spewed into the ambience by utilizing volcanic eruptions and human emissions of aerosols. As we've decreased our aerosol emissions and better our CO2 emissions, human beings have contributed to international warming. we can sort both the organic and human contributions to international warming and cooling much better than human beings imagine, and scientists are confident that lots of the present warming is brought about by utilizing human beings, no longer organic cycles. 2) Meteorologists. Meteorologists have 0 climatology training. in case you ask a meteorologist if something (for instance, better typhoon ability and frequency) is by way of international warming, they can haven't any clue. they are going to probable guess only so as that they sound like experts, yet they quite don't understand. hence stating a meteorologist (like skeptic Jason A does) is thoroughly meaningless. you would possibly want to as well ask Kobe Bryant the thanks to throw a curveball. As an athlete he can guess, and he probable will to maintain his ego, yet in truth he has no idea.

Answer 7

There is another question you need to be able to answer.

4) According to recent research, half of the observed warming is not real but an artifact of poorly sited weather stations giving the temperature record a warm bias. Some of these weather stations are on top of parking lots! If temps are not going up as much as thought, then the climate is not as sensitive to CO2 and other gases as thought. So why are you worried?

To see pictures of some of these weather stations, go to http://surfacestations.org

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I noticed that some of the answers here are spouting inaccuracies from Al Gore's movie. It was a nice touch for louy lefty to provide for you a list of the inaccuracies so you can know which answers not to use in your presentation.

Answer 8

British Judge rules 11 wrong Facts Al Gore in Court
Inaccuracies in Al Gore's An Inconvenient Truth

The decision by the government to distribute Al Gore's film An Inconvenient Truth has been the subject of a legal action by New Party member Stewart Dimmock. Although a full ruling has yet to be given, the Court found that the film was misleading in 11 respects and that the Guidance Notes drafted by the Education Secretary’s advisors served only to exacerbate the political propaganda in the film.

In order for the film to be shown, the Government must first amend their Guidance Notes to Teachers to make clear that 1.) The Film is a political work and promotes only one side of the argument. 2.) If teachers present the Film without making this plain they may be in breach of section 406 of the Education Act 1996 and guilty of political indoctrination. 3.) Eleven inaccuracies have to be specifically drawn to the attention of school children.

The inaccuracies are:

* The film claims that melting snows on Mount Kilimanjaro evidence global warming. The Government’s expert was forced to concede that this is not correct.
* The film suggests that evidence from ice cores proves that rising CO2 causes temperature increases over 650,000 years. The Court found that the film was misleading: over that period the rises in CO2 lagged behind the temperature rises by 800-2000 years.
* The film uses emotive images of Hurricane Katrina and suggests that this has been caused by global warming. The Government’s expert had to accept that it was “not possible” to attribute one-off events to global warming.
* The film shows the drying up of Lake Chad and claims that this was caused by global warming. The Government’s expert had to accept that this was not the case.
* The film claims that a study showed that polar bears had drowned due to disappearing arctic ice. It turned out that Mr Gore had misread the study: in fact four polar bears drowned and this was because of a particularly violent storm.
* The film threatens that global warming could stop the Gulf Stream throwing Europe into an ice age: the Claimant’s evidence was that this was a scientific impossibility.
* The film blames global warming for species losses including coral reef bleaching. The Government could not find any evidence to support this claim.
* The film suggests that the Greenland ice covering could melt causing sea levels to rise dangerously. The evidence is that Greenland will not melt for millennia.
* The film suggests that the Antarctic ice covering is melting, the evidence was that it is in fact increasing.
* The film suggests that sea levels could rise by 7m causing the displacement of millions of people. In fact the evidence is that sea levels are expected to rise by about 40cm over the next hundred years and that there is no such threat of massive migration.
* The film claims that rising sea levels has caused the evacuation of certain Pacific islands to New Zealand. The Government are unable to substantiate this and the Court observed that this appears to be a false claim.

Answer 9

1 - When it was much hotter, coastlines and plant life were very different. That would be very damaging to our modern society, with massive coastal development and intensive agriculture.

Fixing that damage would cost many hundreds of billions of dollars. We're not nomads who can pick up and move. More:

http://environment.newscientist.com/channel/earth/climate-change/dn11647

2. The data shows that, this time, it's not natural. Some good sources to look at:

http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png
http://profend.com/global-warming/

3. See number 1. Also:

http://environment.newscientist.com/channel/earth/climate-change/dn11657

Reading all 26 questions will position well to defeat most any skeptics arguments, although it's a lot of information to deal with:

http://environment.newscientist.com/channel/earth/dn11462

Answer 10

You can answer all three questions with one answer:

The only other time in history that we have seen such a rapid change in global temperature was the Permian Extinction. If people think that climate change will not destroy our natural habitat they are sadly mistaken.