"Recent climate changes, however, cannot be explained by natural causes alone. Research indicates that natural causes do not explain most observed warming, especially warming since the mid-20th century. Rather, it is extremely likely that human activities have been the dominant cause of that warming...

Since the Industrial Revolution began around 1750, human activities have contributed substantially to climate change by adding CO2 and other heat-trapping gases to the atmosphere. These greenhouse gas emissions have increased the greenhouse effect and caused Earth’s surface temperature to rise. The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels...."

http://www3.epa.gov/climatechange/science/causes.html

No. In fact reverse is true.

"Recent climate changes, however, cannot be explained by natural causes alone. Research indicates that natural causes do not explain most observed warming, especially warming since the mid-20th century. Rather, it is extremely likely that human activities have been the dominant cause of that warming...

Since the Industrial Revolution began around 1750, human activities have contributed substantially to climate change by adding CO2 and other heat-trapping gases to the atmosphere. These greenhouse gas emissions have increased the greenhouse effect and caused Earth’s surface temperature to rise. The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels...."

http://www3.epa.gov/climatechange/science/causes.html

The scientific consensus on climate change is "that climate is changing and that these changes are in large part caused by human activities," and it "is largely irreversible."

“Science has made enormous inroads in understanding climate change and its causes, and is beginning to help develop a strong understanding of current and potential impacts that will affect people today and in coming decades. This understanding is crucial because it allows decision makers to place climate change in the context of other large challenges facing the nation and the world. There are still some uncertainties, and there always will be in understanding a complex system like Earth’s climate. Nevertheless, there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations.”

— United States National Research Council, Advancing the Science of Climate Change

https://en.wikipedia.org/wiki/Climate_change

Dear Abhijit,

part of my reply to a recent related questions was:

"(a serious question is) how much natural contributions there are to emissions of greenhouse gasses, often with dangerous positive temperature feedbacks. These are phenomena as melting ice in which dissolved methane is coming out, permafrost melting, smoldering peat soils, ocean bottom and ocean underground emissions of greenhouse gases, which all have been reported recently to occur at a lot of places. We must estimate these natural sources and find ways to reduce their impacts.

"Children will bear the brunt of climate change tomorrow; what present generation need to accomplish in this regard? - ResearchGate. Available from: https://www.researchgate.net/post/Children_will_bear_the_brunt_of_climate_change_tomorrow_what_present_generation_need_to_accomplish_in_this_regard [accessed Dec 4, 2015}"

So I think that your question has to be sorted out again with quantifying those new natural sources, partly with positive temperature feedbacks. Only then can we give a new answer to that question. This should, however, not mean that we should not work with all our forces to reduce manmade emissions.

Kees

By far the most authorative answer is in this report for the United Nations and the World Meteorological Organisation. This is the 5th report in 20 years

You do not have to do your THINKIING just read.

http://www.ipcc.ch/report/ar5/wg1/

No way!

Earth's past climates have been studied in great detail, back to millions and billions of years and courses taught on these, because they contain facts. So is today's climate facts. Those who doubt climate change have something to lose (money and power).

Climate change is the natural process & whether we like or otherwise nature is to remain a powerful energy force covering the total surrounding anywhere & every where.

Unfortunately human factor has vitiated the environment of the nature & we as human beings remain the sufferers  of the same .

In our present day why we are talking including the news in the paper for Global Warming is not the red signal for the people to guards again the warning !!.

We are in the 21 th century with a past historical record & the time has come that we has human being should follow the track of  wisdom  for the survive of human beings .

Climate change is a natural phenomenon but we can not effort to ignore Global warming for the sake of humanity . This is my personal opinion 

AGAIN:

It is an utter disgrace that people present their own amateur thoughts at this scientific site of ResearchGate

The IPCC presents all knowledge in their reports on the status of the science of Climate Change. Everyone who wants to make an entry must show where the IPCC-reports are not right.

ResearchGate is not a gossip-blog

Before venting your thoughts: study the literature; that is a first requirement in science

Natural factors like tectonic movement, volcanoes, sun spots etc. have great role in climate change.

Does anybody have an idea about such offensive down-voting. There are 12 answers, but 18 down-votes!!! This should be treated by RG officials.

Abhijit:

How did you arrive at that figure 80% Natural and 20% due to human factors causing Climate change? In what way human factors can cause any Climate change? Is that a guess, imagination or based on concrete data?

Best

Syed

Dear All,

would it not become high time that the different currents in the discussion natural/anthropogenic do seriously meet and show each other where the differences are? Who is wrong where and why? Just only the idea that we have had the Paris meeting and discussions based on the wrong assumptions! As scientist we must be ashamed that we have not yet scientifically solved the divides.

Cheers, Kees

Abhishek:

Never ever rely on the numerical strength of the adherents of a Hypothesis in Science but only on factual and testable data.

Best

Syed

Ken

Your historic estimate follows mainstream as indicated by you and also available in the IPCC-reports but more important what is your estimate for 2050 or the end of the century?

Ken

This is not about natural phenomena that will give variability as observed over the last century; that is why climate is defined as an average over a period of AT LEAST 30 years. Well 2050 is 30 years from now and that is why I ask for such a base-year but actually the question is the temp in a period of 30-50 year centered around 2050 or 2100.

Ken

You confuse weather and climate; that is why climate is defined so that short term fluctuations like volcanoes ENSO are averaged out. So where do you want to see a relation between the two? CO2 is NOT a cause of ENSO where do you have this idea from

As for volcanoes: happen naturally and why would there be a relation. What is done in historic trend analysis is taking care to handle the years with a major known emission of SO2 into account like the Pinatubo. The effect of such an eruption dies out in say 3 years as was the case with the year without a summer in 1816

Summarising: climate is the AVeRAGE taken over a full period of 30-50 years to be compared to another period of the same length to assess climate CHANGE

I urge you to read at site of Judith Curry the best known denier and climatologist

https://judithcurry.com/2015/11/03/natural-climate-variability-during-1880-1950-a-response-to-shaun-lovejoy/

Great debate, thank you so much for the one who really initiates it, as we know our planet earth, even-though several billions years ago it emerges into existence but we know it based on our life time only. what we are giving to the nature earth it will return it twice the amount. we are taking things which is useful for us from it, and we forcefully pushed the unwanted materials into it. It also keep on trying to clean it but due to over load hopefully it fails in it's duty. we are not at all care for the system what we belongs to; we have to live with someone's hard-work, this is what nowadays all are in need. No one is ready to care the system, so it's completely a human mistake not a natural happenings.

I think climate change was caused, since many centuries back, by 80% natural forces but now a day, it is mainly due to Human activities.

Ken

It is you ignoring to provide SCIENTIFIC references for the clippings you show. I have asked time and time again to proceed in the standard way when a researcher wants to make his point: is this your idea of original research as you call it. I rather start in the accepted way and use the standard encyclopedia of peer-reviewed references as far as I have open access. Furthermore Climate Change is not limited to temp-trend and their analysis but is based on a series of parameters and also on climatology, which is a scientific discipline starting with solar input and atmospheric circulation. Some knowledge is at least required to appreciate the literature

Ken

What about you driving a car: you also find everything out yourself.

And again I did NOT ask for 30 year data but several periods of at least 30 year data because from that CHNGE can be judged

You refuse to consult any other than yourself.

I have asked you over and over again to point out where the information of IPCC is wrong. When you disagree with current scientific status you prove where it is wrong

You can do that the way I just finished a review of a manuscript for a journal

Per page per line you can indicate what is wrong and then  a reply is possible; also because the context is there.

Ken

Ever heard of a sliding average: one cannot refer to ONE single year

Your 1961 for instance would mean the period of say 1945-175 or rather 1940-1980 with a sliding increase of such a period over the previous years/period and later years,period

This means that for say "1925" it is the period 1910-1940 and a good climatologists searches for an apparent fluke/outlier like a volcanic eruption

The Pinatubo is an example: the year 1992 was affected and that means that a 30-year period encompassing it or not differs with a factor o 1/30 of that temperature dip.

http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter10_FINAL.pdf

fig 10.1 on page 879 and its CONTEXT.

Ales

Give references!

Ken

You have to specify where the clippings come from and provide the average over a period of 30 years as a minimum and then a sliding average so that a fluke is noticeable

and furthermore I would not be surprised that there are regions for which main airflow is the dominating climate feature. In N and NL for instance preferential westerlies in winter; a Russian High in summer. Again to average out such situations longer time periods defined climate

The last clipping is not self-explicatory and again why don't you bother to provide the actual reference and/or the context.. The only thing II can read myself is IPCC and AR3 which latter should be TAR

Ken

I have the IPCC report with the worked out science. And you are asking me to single-handedly do what was done there by dozens of sceintists. I have the experience that also in other chapters you need a team to put together all the relevant information

Science is not throwing in data as you like it. Without context I have no way to know where you have your information from and if corrections were or had to be made and why and how. And then you provide an haphazard set from somewhere. Climate Change is about is a change over a large area of the globe not a single city with a set in the twenties and then some other period of ten years in another century.

Harry:

Why do you blindly tend to follow IPCC Report as a holy scripture without applying your own mind? We are really honoured to have you on this string hoping that with your long experience and expertise you would adhere to the rule: "Criticism and the Growth of Knowledge."

Best

Syed

We can not neglect human factors. 

Why we don’t worry about climate change as much as we know we should?!

“If we could invent one risk that bypasses all of our psychological alarm systems, global climate change would be it,” a psychologist explains....

“Changing one’s perception of what scientists think is a non-identity threatening belief to change.”

"...Our research finds that people’s subjective perception of the level of consensus among scientists acts as a “gateway” to other key beliefs that people hold about the issue, such as the belief that climate change is happening, human-caused, and worrisome problem that requires policy support. What’s especially important is the finding that highlighting consensus seems to speak particularly well to those who are often skeptical (e.g., political conservatives). One potential reason for this finding is that changing one’s perception of what scientists’ think is a non-identity threatening belief to change. As such, it appears to be an attractive gateway to changing other personal beliefs. In short, emphasizing agreement may help reduce perceived conflict."

https://www.researchgate.net/blog/post/why-we-dont-worry-about-climate-change-as-much-as-we-know-we-should

Syed

What do you mean with

"blindly tend to follow IPCC": show me where I do

It proves that you did not read the report that I refer to. I strictly cite the first report that means

 Climate Change 2013: The Physical Science Basis

This is written by dozens of climatologists, based on hundreds of publications by climatologists

What I do is to challenge anyone who comes up with his "idea" to show where this is better that what is written on the subject in the report and the references therein. This is the normal scientific way in every publication to do, especially since we are here in a forum called ResarchGate, where everyone can check what the questioners and repliers have contributed to the discipline. RG is thereby verifiable and not an obscure popular blog

I come back to the original question, which is super vague to say the least

1. It says climate change; my question is: change since when and compared to what

2. the percentages mentioned are IMO for the amounts of CO2 of a natural origin versus that made by man. As dr Towe shows the percentage manmade is already higher

Tee real question should thus be: does this increase in CO2 by manmade emissions change climate

There are tow approaches:

1. Data: is there a correlation of CO2 trend and temperature trend

2. Model: basic climatology teaches that there should be a logarithmic relation; however then there is the so-called water feed-back. This means that when temperatures increase more water evaporates and water is a strong greenhouse gas. This works as an amplifier. The debate among climatologists is what the amplification is, based on the past temperature trend.

 In this article, authors have given some data to justify the fact about late Holocene climate changes. Link is given below-

 Late Holocene climate: Natural or anthropogenic?https://www.academia.edu/22359588/Late_Holocene_climate_Natural_or_anthropogenic

Harry:

Thanks for your kind response, but I must say that there is serious contradiction in what you claim. The IPCC Report 2013: The Physical Science Basis, is based on the work of dozens of reputed Scientists and hundreds of publications.Then why should you alone be challenging everyone? Let IPCC take a call on this.This subject has already been amply discussed in the past and is on the records of previous strings at RG, which need not be repeated now. Climate Science with several unpredictable parameters needs highly erudite attitude of mind to seek and discover practical solutions through empathetic discussions with Scientists.

Best

Syed

Syed

Indeed it appears that serious climatologists do not even bother to contribute to RG. In fact I also "unfollowed" many of the questions in the topic of Climate Change because of the obvious unscientific questioning and replying. It is for dr Towe who keeps me alert that I still contribute to a few of these for instance this question

Dear all

What documentation is there that in the ice age was high carbon dioxide in the atmosphere?

How is it calculated that 80% of climate change are natural and 20% are human?

Where did these numbers come from?