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there are still some skeptics when it comes to climate change, but majority of the population are no longer in denial,this is an interesting read.

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Up until a few years ago, Richard Muller was often quoted by sceptics as a credible, high-profile scientist who doubted the consensus on climate change.

Today, he starts his lectures by stating a few things he believes to be facts.

"Al Gore has grossly exaggerated global warming. And if you watch his movie you have more misinformation than information.

"However, global warming is real. It is caused by humans. It is caused by the human emission of greenhouse gases, and I personally feel we have to stop it somehow."

In 2010, Professor Muller from Berkeley University was funded to carry out a comprehensive study by a group of individuals who doubted the Intergovernmental Panel on Climate Change (IPCC) data.

They believed that urban heat islands, data-selection bias, and inaccurate climate models were being glossed over by scientists.

'Don't trust us' approach key to convincing sceptics

Professor Muller and his team - all of whom doubted climate change was happening or that carbon dioxide was its cause - were shocked to find a correlation between carbon dioxide emissions and warming.

"That was the biggest surprise of all," he said.

"Volcanoes, sunspots, orbital changes, we could all rule out. What we could do is show [that warming] matched the carbon dioxide exceedingly well."

To address what he sees as a lack of transparency in some IPCC reporting, his team made all their data available online.

"The teams that did [the previous studies] said 'trust us'. We said 'don't trust us, here's what we did'. And for that reason I think we were able to win over the sceptics," he said.

However, he said there was still room for scepticism.

"Yes I am a converted sceptic. However, anybody today who is not a sceptic about the solutions being proposed is not thinking them through."

Dr Anthony Purcell, Research Fellow, ANU

"I doubted that the climate could be so dramatically sensitive to small perturbations, especially on a short timescale," Anthony Purcell said of his initial position on climate change.

Dr Purcell, a mathematician and geophysicist, said his view was largely shared by the members of his social circle.

"Pretty much everybody in my personal life was either agnostic or deeply hostile to the concept of anthropogenic climate change," he said.

"[My father is] a deeply entrenched climate denialist."

In 2010, he read an article in The Australian newspaper in which the distinguished scientist Professor Frank Fenner predicted that "Homo sapiens will become extinct, perhaps within 100 years" due to climate change.

Dr Purcell said that statement shook him.

"This was a responsible scientist making a public declaration and it seemed to me to raise alarm bells," he said.

"I hadn't been aware that this was even something that might be considered as a possible outcome."

Personal relationships 'severely eroded' by change of view

A deep-sea core sample, containing layers of sediment laid down over millions of years, demonstrated first-hand that Professor Fenner's prediction had a historic precedent.

One of the layers in the core sample was around 55-million-years old, from what is known as the Palaeo-Eocene thermal maximum (PETM).

"All of a sudden that [carbon-rich material in the sediment] vanishes and it's just this dingy mud with no evidence of biological activity at all," he said.

"That was a response to a four-degree temperature increase that occurred over 20,000 years. We're looking at something that's a hundred-times faster than that."

Dr Purcell said his acceptance of the climate science had a significant personal toll.

"It's deeply impacted my relationship with my father," he said.

"It's severely eroded our relationship and our ability to communicate."

Professor David Karoly, University of Melbourne, Atmospheric Science

David Karoly is one of the world's pre-eminent climate scientists, and advises the Australian Government through the Climate Change Authority (CCA).

But back in 1986, he believed he had a way to prove climate change had nothing to do with carbon emissions.

"I was aware from theoretical considerations that we would expect a specific pattern of temperature changes associated with increasing greenhouse gases," he said.

"Which is warming in the lower atmosphere and cooling in the stratosphere at heights above 15 kilometres.

"And I thought I would use that signature to show that in fact what was actually occurring in the data was due to natural variability like El Nino or increasing sunlight, and not due to human-caused climate change."

Professor Karoly submitted an abstract of his forthcoming research to a climate-change conference in Melbourne in 1986. He expected his findings to show that there was no carbon-driven-warming signature.

"The more I looked, the more I found this signature of warming in the lower atmosphere and cooling in the upper atmosphere," he said.

By the time he came to present his paper, he had to switch his position in support of anthropogenic climate change.

But that was the '80s and climate science had yet to be deeply politicised.

He says changing his view on climate change was not a big deal at the time.

"I was coming into it as what I believe all scientists are - sceptical and wanting to test a hypothesis - and that's what I did."

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What convinced these scientists climate change is real?

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Up until a few years ago, Richard Muller was often quoted by sceptics as a credible, high-profile scientist who doubted the consensus on climate change. Today, he starts his lectures by stating a few things he believes to be facts. "Al Gore has grossly exaggerated global warming.

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Facts about why it is happening

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Climate Change: Vital Signs of the Planet

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The Greenhouse Effect

Increasing Greenhouses Gases Are Warming the Planet

Scientists attribute the global warming trend observed since the mid-20 th century to the human expansion of the "greenhouse effect" ¹ - warming that results when the atmosphere traps heat radiating from Earth toward space.

Life on Earth depends on energy coming from the Sun. About half the light energy reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and radiated in the form of infrared heat. About 90% of this heat is then absorbed by greenhouse gases and re-radiated, slowing heat loss to space.

Gases that Contribute

The Role of Humans

Human Activity Is the Cause of Increased Greenhouse Gas Concentrations

Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO ₂). This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make CO ₂. To a lesser extent, clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases.

How do we know what greenhouse gas and temperature levels were in the distant past?

Ice cores are scientists' best source for historical climate data. Other tools for learning about Earth's ancient atmosphere include growth rings in trees, which keep a rough record of each growing season's temperature, moisture and cloudiness going back about 2,000 years. Corals also form growth rings that provide information about temperature and nutrients in the tropical ocean. Other proxies, such as benthic cores, extend our knowledge of past climate back about a billion years.

detailed answer

The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels by nearly 50% since 1750 ². This increase is due to human activities, because scientists can see a distinctive isotopic fingerprint in the atmosphere.

In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of scientific experts from countries all over the world, concluded thatit is unequivocal that the increase of CO ₂, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere.

"Since systematic scientific assessments began in the 1970s, the influence of human activity on the warming of the climate system has evolved from theory to established fact."

- Intergovernmental Panel on Climate Change

The panel's AR6 Working Group I (WGI) Summary for Policymakers report is online at https://www.ipcc.ch/report/ar6/wg1/.

Is the Sun to Blame?

Evidence Shows That Current Global Warming Cannot Be Explained by Solar Irradiance

Scientists use a metric called Total Solar Irradiance (TSI) to measure the changes in energy the Earth receives from the Sun. TSI incorporates the 11-year solar cycle and solar flares/storms from the Sun's surface.

Studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with increased volcanic activity helped trigger the Little Ice Age.

The above graph compares global surface temperature changes (red line) and the Sun's energy that Earth receives (yellow line) in watts (units of energy) per square meter since 1880. The lighter/thinner lines show the yearly levels while the heavier/thicker lines show the 11-year average trends. Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious.

The amount of solar energy that Earth receives has followed the Sun's natural 11-year cycle of small ups and downs with no net increase since 1880. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Credit: NASA/JPL-Caltech

But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:

Since 1750, the average amount of energy from the Sun either remained constant or decreased slightly³.

If a more active Sun caused the warming, scientists would expect warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere and a warming at the surface and lower parts of the atmosphere. That's because greenhouse gases are slowing heat loss from the lower atmosphere.

Climate models that include solar irradiance changes can't reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.
References
References

1. IPCC 6 th Assessment Report, WG1, Summary for Policy Makers, Sections A, " The Current State of the Climate "

IPCC 6 th Assessment Report, WG1, Technical Summary, Sections TS.1.2, TS.2.1 and TS.3.1

2. P. Friedlingstein, et al., 2022: "Global Carbon Budget 2022", Earth System Science Data ( 11 Nov 2022): 4811-4900. https://doi.org/10.5194/essd-14-4811-2022

3. IPCC 6 th Assessment Report, WG1, Chapter 2, Section 2.2.1, " Solar and Orbital Forcing"

IPCC 6 th Assessment Report, WG1, Chapter 7, Sections 7.3.4.4, 7.3.5.2, Figure 7.6, " Solar"

M. Lockwood and W.T. Ball, Placing limits on long-term variations in quiet-Sun irradiance and their contribution to total solar irradiance and solar radiative forcing of climate," Proceedings of the Royal Society A, 476, issue 2228 (24 June 2020): https://doi 10.1098/rspa.2020.0077

Header image credit: Pixabay/stevepb

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Vital Signs of the Planet: Global Climate Change and Global Warming. What is the "greenhouse effect"? What is causing it? Are humans to blame? What does solar irradiance have to do with it? Answers here.

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Environment
Wildlife
Food Source
increase in extreme weather
bush fires

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walk instead of drive.

turn off all electronics when not in use

energy efficient buildings

eat smarter

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A briefs history of climate change

A briefs history of climate changehttp://www.bbc.com/news/science-environment-15874560