ROCKY REX'S SCIENCE BITES

Carbon dioxide is always in the atmosphere as part of the Earth's  carbon cycle. The global carbon cycle transfers carbon through the Earth’s different parts -  the atmosphere, oceans, soil, plants, and animals.  So carbon moves around — it flows — from place to place. Carbon dioxide (CO 2 ) is the main  greenhouse gas  emitted through human activities.  Human activities  are changing the carbon cycle. First, by adding more CO 2  to the atmosphere, mainly by  burning fossil fuels . Also by changing the ability of  natural sinks , like forests, to remove CO 2  from the atmosphere.  Human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.   The  carbon sinks,  on land and in the oceans, have responded by increasing the amount of carbon they absorb each year. Carbon sinks cope with  about half  of human greenhouse ga...

Atmospheric carbon dioxide concentration  is now around 400 parts per million (ppm). It last reached similar levels during the  Pliocene , 5.3-2.6 million years ago.   Outcrop of Middle Pliocene diatomaceous lake beds at Ledi Geraru, northern Afar region of Ethiopia. (photo: Roy Johnson.) In the middle Pliocene,  the concentration of carbon dioxide in the air ranged from about 380 to 450 parts per million.   During this period, the area around the North Pole was much warmer and wetter than it is now. Summer temperatures in the Arctic were around 15 degrees C , which is about 8 degrees C warmer than they are now. Global average temperatures were 2-3°C warmer than today. Sea level was up to 40 metres higher than now. Of course, there were no modern humans at that time. Hominids of the Pliocene Nor was there a  global system of food supply   relying on stable climates for agriculture.

Arctic permafrost – ground that has been frozen for many thousands of years – is now thawing because of global climate change. “The release of greenhouse gases resulting from thawing Arctic permafrost could have catastrophic global consequences,” said  Dr. Max Holmes, a Senior Scientist at the Woods Hole Research Center (WHRC). Schematic diagram of  greenhouse gas es and permafrost.   Graphic by John Garrett. Thawing permafrost releases greenhouse gases (carbon dioxide and methane) into the atmosphere, which accelerate climate change, which in turn cause more thawing of the permafrost.  This may be a fairly slow process, and there is a lot more research to be done in this area. Some scientists fear that this potentially unstoppable and self-reinforcing cycle could produce a dangerous "tipping point".

Oceania  is a region made up of thousands of  islands throughout the Central and South  Pacific Ocean.   It includes Australia, the smallest continent in terms of total land area. Many of the nations in Oceania are  Small Island Developing States (SIDS). Many scientists say that Oceania is more vulnerable than most parts of the Earth to climate change, because of its climate and geography.  The heavily coastal populations of the continent’s small islands are vulnerable to flooding and erosion  because of  sea level rise.   An international team of researchers  has produced this graph of ocean levels, for a period of time going back to around 500 BC.  Five of the Solomon Islands have been swallowed whole by rising sea levels between 1947 and 2014.  "It’s a perfect storm,” says  Simon Albert  of the University of Queensland. “There’s the background level of global sea-level rise, and then the add...

Heat can affect things without causing a temperature rise. Extra heat can be used in ‘ changing state ’ instead of raising temperature. A change of state could be … a  solid  melting to a  liquid .  Or a  liquid  evaporating to a  gas . So  heat is needed to change ice at zero degrees C to water at zero degrees C. And to change water into water vapour….. without raising the temperature. Scientists call the heat used to change state  latent heat. Also, there are natural variations in the global climate,  El Nino  events being the ones that affect world temperature the most. The opposite to 'El Nino' is 'La Nina', a cooling effect. If global temperatures are plotted on a graph in a way that shows these variations, it makes the overall warming trend very obvious. Every La Nina year since 1998 has been warmer than every El Nino year before 1995. As the Earth warms, each El Nino event 'rides' on a higher base...

Deltas  often form when rivers reach the sea. The river can carry sand and mud when it is flowing fast. As the water enters the sea, it s lows down , and the sediment drops to make the delta. Many deltas are at risk from climate change.   This map shows the levels of risk. An estimated 80 percent of the world's megacities are located in fragile river deltas.   A megacity has a population of over 10 million people. Over 500 million people live on deltas. Why are deltas at risk? One reason  is  rising sea level , which wears away the delta from the front. Deltas are an example of the complex processes that happen along coastlines.

The  northern hemisphere  winter  , December 2015 to February 2016 , was the warmest in the records.  The average temperature, taken for northern land and ocean surfaces, was  1.13°C above the 20 th   century average.  This was the highest for December, January and February in the 1880–2016 record, passing the previous record of 2007 by 0.29°C. December 2015–February 2016 also marks the highest 3-month departure from average for any 3-month period on record. It is interesting to note that there were some 'cold spots'. There is an obvious 'blue blob' in the North Atlantic.  Some scientists have linked this to melt-water from Greenland. “It is conspicuous that one specific area in the North Atlantic has been cooling in the past hundred years while the rest of the world heats up,” says Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research. The accumulated monthly total mass balance of the Greenland ice sheet measure...

When the last glacial period ended about 11,500 years ago, the Earth's modern climate began to develop.  The large continental ice sheets shrank, and sea level rose. Around 8,200 years ago, however, a major cooling event occurred.  The   8.2 ka event   was first discovered in the Greenland ice core  GISP2. Over two decades temperature cooled about 3.3°C in Greenland . Temperatures in Europe dropped by around 2 °C. The entire event lasted about 150 years. Then temperatures warmed, returning to their previous levels.  So what caused the 8.2 ka event? As the large ice sheets in Canada were melting, a large  meltwater lake  formed south of the Hudson Bay.   Geologists have named this  Lake Agassiz , after the  19th century scientist Louis Agassiz. It was dammed to the north by the  Laurentide  ice sheet . Slowly, the ice melted further, and the lake emptied into the sea in a...

Space is not very far away. Aircraft on long-haul flights travel at a height of about 10 km. The lowest layer of the atmosphere, the  Troposphere,  ends at about 15 km. The air in the layers above the troposphere is very thin indeed. Think of a place around 15 km (9 miles) from where you are. That's pretty much how near you are to space. All the waste gases people dump into the air are trapped in the thin layer of air around the Earth. Molecules  in the air include nitrogen and oxygen as well as water, carbon dioxide, ozone, and many other compounds in trace amounts, some created naturally, others the result of human activity. In addition to gases, the atmosphere contains extras such as smoke, dust, acid droplets, and pollen. Atmospheric concentrations  of some  greenhouse gases  over the last 2,000 years.  Increases since about 1750 are due to human activities in the industrial era.  Concentration units are  parts pe...

Between about 20,000 and 5,000 years ago, Earth slowly changed from the frigid conditions of an  Ice Age , to the world on which our civilization has developed. As the  ice sheets  melted, colossal volumes of  water  flowed back into the oceans. The  pressures  acting on the Earth's crust changed as a result.  The  weight of ice  on the continents was reduced, and the rising seas put  extra water pressure  on the seafloors. In response, the  crust  moved up and bent, creating extra volcanic activity, increased seismic shocks and giant landslides. So if we continue to allow greenhouse gas emissions to rise unchecked, causing serious warming, will our planet's crust react once again? In Alaska, climate change has pushed temperatures up by more than 3 degrees Celsius in the last half century, and  glaciers  are melting at a staggering rate, some losing up to 1 kilometre in thickness in the last 10...

The global average temperature for March 2016 was 13.92 °C,  according to the   US National Atmospheric and Oceanic Administration. This is the highest March average temperature in the 1880–2016 record, at 1.22°C  above the 20 th  century average of 12.7°C . This marks the highest monthly temperature departure among all 1,635 months on record, beating the previous all-time record set just last month by 0.01°C.  Overall, the nine highest monthly temperature departures in the record have all occurred in the past nine months.  March 2016 also marks the 11 th consecutive month a monthly global temperature record has been broken, the longest such streak in NOAA's 137 years of record keeping.

Hurricanes, cyclones, and typhoons are all the same weather phenomenon. We use those different names for these  tropical storms  in different places.  In the Atlantic and North-East Pacific, the term  “hurricane”  is used. So far,  Hurricane Patricia  is the strongest hurricane recorded at landfall.  Image of Hurricane Patricia tweeted by  astronaut Scott Kelly . In the North-West Pacific a tropical storm is called a  “typhoon” , and  “cyclones”  occur in the South Pacific and Indian Ocean. Three strong tropical storms  (Kilo ,  Ignacio , and  Jimen a) ,  formed in the Pacific in 2015.  On Sunday 30th August, all of them were a category 4.  This was the first time the north-eastern Pacific had seen three category 4 hurricanes at the same time. Multiple cyclones in the Pacific Ocean in 2015 Tropical storms  can’t form outside the tropics - water temperatures are too cold. Sea su...

Marlin  can hunt in water a half mile down, and sailfish often dive deep too. In more and more places around the world, ocean predators are sticking near the surface. Why? Warming temperatures are  sucking oxygen out of waters  even far out at sea, making enormous stretches of deep ocean hostile to marine life. Vast stretches of the ocean interior  suddenly lost oxygen  during the transition out of the last  glacial stage , between 17,000 and 10,000 years ago.  This event was the most recent example of large-scale global warming.

This graph shows how  carbon dioxide  has increased and decreased over hundreds of thousands of years. The low readings match with times called ' glacial stages '. During glacial stages,  ice  covered large areas of the Earth. The peaks in the graph show times when carbon dioxide was high, matching times called ' interglacial stages '. The most recent glacial stage occurred between about 115,000 and 11,500 years ago.   The  last interglacial period  occurred before it, from around 130,000 to 115,000 years ago. It's official international name is the  Eemian,  but it has other names in specific places. Climate information from that time is particularly useful. During that time,  temperatures  on earth were higher at the poles than they are now.  The  sea level  was between five and nine metres higher than current levels, because of the melting of ice in  Greenland  and  A...

July 2015 was the warmest month in the modern temperature record. The average temperature for July 2015 across global land and ocean surfaces was 1.46°F (0.81°C) above the 20 th  century average, according to the  United States National Oceanic and Atmospheric Administration. They said: "As July is  climatologically the warmest month for the year , this was also the all-time highest monthly temperature in the 1880–2015 record, at 16.61°C, surpassing the previous record set in 1998 by 0.08°C." Globally-averaged temperatures for the year 2015 beat the previous record set in 2014 by 0.13 degrees Celsius.  NASA analysis estimates 2015 was the warmest year with 94% certainty. Most of the warming occurred in the past 35 years, with 15 of the 16 warmest years on record occurring since 2001. 2015 was the first time the global average temperature was 1 degree Celsius or more above the 1880-1899 average. Global annual average temperature re...