Dear Ricardo:

To my knowledge, there is a consensus in the scientific community --as you know, consensus does not imply unanimity, but a vast majority-- that the main cause of climate change is human activity. That's why many countries are aiming to take costly steps to address the problem. 

n the Forward of "Climate Change 2013: The Physical Science Basis" reported by Intergovernmental Panel on Climate Change (available at http://www.ipcc.ch/report/ar5/wg1/), the following statement is given:

"Climate Change 2013: The Physical Science Basis" presents clear and robust conclusions in a global assessment of climate change science— not the least of which is that the science now shows with 95 percent certainty that human activity is the dominant cause of observed warm- ing since the mid-20th century. The report confirms that warming in the climate system is unequivocal, with many of the observed changes unprecedented over decades to millennia: warming of the atmosphere and the ocean, diminishing snow and ice, rising sea levels and increasing concentrations of greenhouse gases. Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. These and other findings con rm and enhance our scientific understanding of the climate system and the role of greenhouse gas emissions; as such, the report demands the urgent attention of both policy-makers and the general public.

For further details, please see the report. I think that this report is the most reliable among different views.

Climate is always changing. But  the main causes which is accelerating it  are: WAR, Weapons, Bomb and Nuclear development.

Ken,

You are dead wrong again.

"In the first edition of On the origin of species (1859), Darwin had estimated that the erosion of the Sussex Weald must have taken 300 million years.[9]p314 Both he and Lyell were surprised when the physicist William Thomson (Lord Kelvin) said the Earth could not be as old as they thought."

https://simple.wikipedia.org/wiki/Age_of_the_Earth

There was no consensus that Lord Kelvin was correct.

Very interesting discussion and the issue , which we will continue to witness , perhaps unfinished debate ..? . I am not a climate scientist , but i wonder,  still we do not have  a concensus on this issue , whether or not , climate  change is anthropogenic or non-anthropogenic in nature . On the contrary ,  climate has changed ,  as evident from geological records , ice cores, sediment cores etc..There is no single theory of climate change .But green house theory is very near to describe the climate change ..?

People say that we are facing a global warming. But I noticed that winters are more cold.

Cesar

Where did you "notice" the cooler winters yourself?

NB a change means a change of an average parameter of climate, for instance temperature, which means the average over a period of 30 years compared relative to an earlier period of 30 years

In short: Climate is NOT weather and it is not the temperature in your local environment

There was a consensus when Lord Kelvin published his calculation of the age of the Earth. The consensus was that he was wrong. It had been known since 1788, when James Hutton showed John Playfair and Sir James Hall the unconformity at Siccar Point that the Age of the Earth was vast.

http://edinburghgeolsoc.org/downloads/lbgcleaflet_siccarpoint.pdf

In the previous link I gave Thomas Huxley also did not accept Lord Kelvin's age, and Kelvin recalculated it but failed to get a more acceptable answer.

Darwin's calculations for the  age for the Cretaceous rocks of the South Downs is spelt out in "The Origin of Species". His over estimation of the time taken to erode the Jurassic Weald at 300 Ma is out by a factor of ten.

But Lord Kelvin was wrong about the physics. Heat is transferred to the surface by convection not conduction as he imagined. The contribution of radio activity was not his main omission but it was used to find the correct age of the Earth at 4.543 Ba.

So just as it was known that the age of the Earth was much greater than Kelvin's calculation, so too is it is now known that increasing the concentration of CO2 in the atmosphere causes global warming. Venus and Mars show that, and there is plenty of geological evidence to show that the Earth was warmer when CO2 levels were greater. What is not known is climate sensitivity - the relationship between CO2 concentration and global temperatures.

So just as Lord Kelvin was wrong and everyone knew it, so too is Dr Towe who asserts without any proof that threat to the climate from anthropogenic CO2 is not significant.

The human activities related to power generation using fossil fuels whether coal, oil or gases is the direct reason for the climate change. This issue is accepted for all scientists all over the word. However, who write against this trend is pens which are purchased with petrol-dollars.

Regards

it's because of what the people change in the earth by reducing the jungles ,cut the trees, more pollutants so the climate change was occurred by the human.

Ken

What has climate (change) to do with Darwin measuring some local temperatures during his voyage.

And yes the 30 years are arbitrary and it seems that a period of 60 years is a better choice. So a period of 4 years, the most recent ones or even 20 years are not to barely significant in comparing those with past periods of the same length. And you keep on using a single base year as the reference.

So my question why 1997 and not a period of say May 11th 1995 -10 May 1996 as the arbitrary base period

Ken

Clomate Change is about a global increase in temperature of 2 C at a CO2 doubling. Thus for a 40% increase in CO2 it should be close to ONE degree C. And again this is for the globally averaged stations and without being so stupid to present that in  absolute values but as a change because a difference has a much higher precision

Ken

A single year is NOT a CLIMATE issue and then there is a hiatus and then NOAA, what can I do with such vagueness

Darwin was measuring a temperature at a site for a day or so: what has this to do with CLIMATE

What do you mean with "the climate" in reference to Darwin and different in what should it be today? Climate Change is on a temperature increase of stations that are representative of a larger area and then averaged over the globe.

Ken

Darwin produced CLIMATE data?! you must be kidding?  A  snapshot on his voyages, with uncalibrated instruments and not done according to the strict precautions in a measuring box

What should I have read about NOAA that disappeared. What is this riddle

Ken

Shows you do not understand climate

I stick my neck out because the question begs for an answer and clarification. By "origin of climate change" I presume we are speaking of human-induced climate change as distinct from the natural changes that would occur were we not around. The natural variabiliy of climate in our absence is inferred tfrom he paleoclimate data and analyses and is a given. So now we come along and add our contribution be there any to whatever Nature would have wrought had we not been present. But the problem is nonlinear and we have to separate wheat from chaff in a complicated mix of inputs and forcing functions and data. I return to my soapbox that there is no smoking gun, there is only an accumulative aggregate of indicators and analyses that in sum yield a plausible line of inference that we are experiencing secular global climate change induced in all or in part by human activity. 

I agree with you except that I don't think that the science is settled but there is enough of it to warrant our taking action now while we can and while we as default keepers of the planet have the means.