Fun picture for your enjoyment:
Tuesday, March 9, 2010
New Posts
I know, it has been awhile. I am making up for lost time. The following 4 posts are probably best if viewed in order (that is if you are Mann enough to read them.... wow, bad science joke my apologies. It has been a long blog session.) Anyway, start from the first climate change entry and work your way to the top if you dare! And PLEASE comment or question! Thanks!
Fun picture for your enjoyment:
Fun picture for your enjoyment:
Monday, March 8, 2010
climate change: atmospheric carbon dioxide levels
This is what ultimately makes me believe that current levels of climatic change are influenced by human activity:
Current carbon dioxide levels are able to be measured by simply measuring the air itself, in Mauna Loa, a method created by Charles Keeling in the 50's. These records were compared to the ice core CO2 records I have been talking about, and they lined up.
As you can see, the increase in CO2 seems to coincide also with an increase in fossil fuel use.
This is one of my favorite graphs. Again, an ice core record (this data is from Vostok, an Antarctic ice core), showing carbon dioxide levels graphed for the past 400,000 years. This patterned records back about 650,000years (as shown in previous post).
Atmospheric carbon dioxide levels increase and decrease on a cycle, between approximately 180 and 290 ppmv (parts per million by volume). However, current measured levels of carbon dioxide in the atmosphere are ~390 ppmv. In other words, the amount of carbon dioxide in the atmosphere presently is almost 1.5X higher than it has been for the past 650,000 years.
This is what has me sold. This does not fit any sort of natural cycle that we have seen, and it seems to line up with the increase in fossil fuel burning in an exact manner.
Current carbon dioxide levels are able to be measured by simply measuring the air itself, in Mauna Loa, a method created by Charles Keeling in the 50's. These records were compared to the ice core CO2 records I have been talking about, and they lined up.
As you can see, the increase in CO2 seems to coincide also with an increase in fossil fuel use.This is one of my favorite graphs. Again, an ice core record (this data is from Vostok, an Antarctic ice core), showing carbon dioxide levels graphed for the past 400,000 years. This patterned records back about 650,000years (as shown in previous post).
Atmospheric carbon dioxide levels increase and decrease on a cycle, between approximately 180 and 290 ppmv (parts per million by volume). However, current measured levels of carbon dioxide in the atmosphere are ~390 ppmv. In other words, the amount of carbon dioxide in the atmosphere presently is almost 1.5X higher than it has been for the past 650,000 years.This is what has me sold. This does not fit any sort of natural cycle that we have seen, and it seems to line up with the increase in fossil fuel burning in an exact manner.
climate change: the famous hockey stick
So, more recently we are in a naturally warming or interglacial period. However, climate records show that temperatures and greenhouse gases are increasing significantly more than they have in the past.
I wont go into this graph too much. This is the famous 'hockey stick' graph that has gotten so much recent attention with Climategate. (my advisor's opinion on the matter here). It shows measured temperature changes for the past 2000 years from many different sources. Each color represents a different study. It appears as if global temperatures have increased significantly in recent years. From what I understand, the 'trick' that they spoke of in these emails refers to a statistical method that is used to portray changes in graphed data such as this. It is extremely common to use, and is not in fact used to trick people into believing that climate change is real. However, what is not good practice (and I believe makes any scientist seem suspicious) is not to publish your raw data, or to allow the public access to it online.
Even with these arguments against the scientists who published a few of these papers, it seems pretty irrefutable that something is going on here. There have been many studies independent of Climategate that have made the same claims:
1. Paleoclimate paper by Glen MacDonald:
2. Work by NASA:
3. Collaborative paper published in Science compared to Mann et al's work (study sites shown at top):
(all slides courtesy of Dr. Glen MacDonald)
I'm sorry if this is an overkill of climate change graphs, but I would show more if I could. I just want to say that global climate has been warming. And in recent years (since the industrial revolution) it has been very rapidly warming; certainly more than a natural cycle would cause. This pattern has been found in many different studies, using different proxies and different techniques, in many areas of the world.
Climate models that simply use natural warming cycles as inputs do not yield the warming we have seen and measured (such as in these graphs). What is causing that extra warming? Some argue that solar forcing, or increased volcanic activity is the cause. However, when solar forcing patterns are added to climate models, the yield still does not reach current day warming. This leads many to believe that humans are the cause for the extra warming push.
I wont go into this graph too much. This is the famous 'hockey stick' graph that has gotten so much recent attention with Climategate. (my advisor's opinion on the matter here). It shows measured temperature changes for the past 2000 years from many different sources. Each color represents a different study. It appears as if global temperatures have increased significantly in recent years. From what I understand, the 'trick' that they spoke of in these emails refers to a statistical method that is used to portray changes in graphed data such as this. It is extremely common to use, and is not in fact used to trick people into believing that climate change is real. However, what is not good practice (and I believe makes any scientist seem suspicious) is not to publish your raw data, or to allow the public access to it online.
Even with these arguments against the scientists who published a few of these papers, it seems pretty irrefutable that something is going on here. There have been many studies independent of Climategate that have made the same claims:
1. Paleoclimate paper by Glen MacDonald:
2. Work by NASA:
3. Collaborative paper published in Science compared to Mann et al's work (study sites shown at top):
(all slides courtesy of Dr. Glen MacDonald)I'm sorry if this is an overkill of climate change graphs, but I would show more if I could. I just want to say that global climate has been warming. And in recent years (since the industrial revolution) it has been very rapidly warming; certainly more than a natural cycle would cause. This pattern has been found in many different studies, using different proxies and different techniques, in many areas of the world.
Climate models that simply use natural warming cycles as inputs do not yield the warming we have seen and measured (such as in these graphs). What is causing that extra warming? Some argue that solar forcing, or increased volcanic activity is the cause. However, when solar forcing patterns are added to climate models, the yield still does not reach current day warming. This leads many to believe that humans are the cause for the extra warming push.
climate change: Milankovich cycles
Some people have heard that the earth naturally warms and cools, and that we are in a natural warming period right now. According to paleoclimate records this is true. The Earth has gone through glacial (icy/cold) and interglacial (warm) cycles (1 cycle every ~10,000 years) for the past 400,000-650,000 years approximately.
We can tell that this has been happening because of greenhouse gases preserved in ice cores, and oxygen isotopes (as mentioned in a previous post). Here is a figure of the glacial/interglacial cycles (this shows methane in red and carbon dioxide in blue - present day is on the left and 650,000 years ago to the right.) This is from an ice core in Antarctica (Vostok). You can see that we are indeed in a warming cycle currently.
So, what causes these cycles? The theory behind this is called the Milankovitch Theory of Glaciation. This Serbian dude Milutin Milankovitch proposed it in the early 20th century. He said that there are three factors regarding the earth's orbit that cause glacial and interglacial cycles:
1. Eccentricity - the shape of the Earth's orbit around the sun is not a perfect circle, and the 'oblong-ness' of this orbit changes every ~100,000 years.
2. Obliquity - the tilt of the earth's axis. This affects the seasons on earth, and changes every 41,000 years.
3. Precession of the equinoxes - wobble of the earth - the earth spins, almost like a top. just as a top wobbles, so does the earth. This wobble changes every 23,000 years.
When the eccentricity is more oblong, and the tilt is less, and the Northern Hemisphere is tilted away from the sun the earth will enter a glacial period. This lineup causes summers to be less warm on average, so that ice does not melt away as much each year, causing an ice buildup. The Northern hemisphere must be pointed away from the sun, because ice builds up easier in the North since there is land surrounding the Arctic. The Antarctic is surrounded by water, and since ice builds up more easily on land, ice will form more easily in the north (Arctic).
As more and more of this ice builds up, more light is reflected off of the ice. (Ice reflects light/heat since it is white, whereas open water/land absorbs light/heat). Since more light and heat are being reflected off of the earth's surface, the earth cools and enters an ice age. These cycles of the earth entering an ice age (and the opposite happens for entering a warm period or 'interglacial cycle') are what are reflected in the first graph in this post. These cycles of the Milankovitch Theory have been confirmed by marine cores.
We can tell that this has been happening because of greenhouse gases preserved in ice cores, and oxygen isotopes (as mentioned in a previous post). Here is a figure of the glacial/interglacial cycles (this shows methane in red and carbon dioxide in blue - present day is on the left and 650,000 years ago to the right.) This is from an ice core in Antarctica (Vostok). You can see that we are indeed in a warming cycle currently.
So, what causes these cycles? The theory behind this is called the Milankovitch Theory of Glaciation. This Serbian dude Milutin Milankovitch proposed it in the early 20th century. He said that there are three factors regarding the earth's orbit that cause glacial and interglacial cycles:
1. Eccentricity - the shape of the Earth's orbit around the sun is not a perfect circle, and the 'oblong-ness' of this orbit changes every ~100,000 years.
2. Obliquity - the tilt of the earth's axis. This affects the seasons on earth, and changes every 41,000 years.
3. Precession of the equinoxes - wobble of the earth - the earth spins, almost like a top. just as a top wobbles, so does the earth. This wobble changes every 23,000 years.
When the eccentricity is more oblong, and the tilt is less, and the Northern Hemisphere is tilted away from the sun the earth will enter a glacial period. This lineup causes summers to be less warm on average, so that ice does not melt away as much each year, causing an ice buildup. The Northern hemisphere must be pointed away from the sun, because ice builds up easier in the North since there is land surrounding the Arctic. The Antarctic is surrounded by water, and since ice builds up more easily on land, ice will form more easily in the north (Arctic).As more and more of this ice builds up, more light is reflected off of the ice. (Ice reflects light/heat since it is white, whereas open water/land absorbs light/heat). Since more light and heat are being reflected off of the earth's surface, the earth cools and enters an ice age. These cycles of the earth entering an ice age (and the opposite happens for entering a warm period or 'interglacial cycle') are what are reflected in the first graph in this post. These cycles of the Milankovitch Theory have been confirmed by marine cores.
climate change: some general terms
A common question I get is "Is global warming real and/or are we causing it?" Well, all science is technically theory, but in my opinion (based on what I have read) the climate is certainly warming and we are impacting it as well.
I'm giving a presentation on climate change this week, so will be attempting to break it down over the next few posts. Hopefully it's not too intense - for my 3 followers haha. Also, please comment! I'm not saying I'm right and am always looking for ideas/inputs!
To start off, some wicked fun definitions!
1. global warming - refers to global temperature increases we have experienced since the mid 20th century. Thought to be caused by human activity.
2. climate change - any change in the statistical distribution of weather. Can be either a change in the average or a change in the order of events surrounding the average. Can occur once, or in a cyclical pattern, over decades to millions of years. ex: El Nino, glacial and interglacial periods (ice ages), the Dust Bowl, etc.
3. global weirding - I just heard this the other day. an increase in severe or unusual environmental activity. This speaks to the fact that the earth isn't getting warmer everywhere. Some places may get colder, some may experience monsoons, and some drought.
4. greenhouse effect - caused because of the gases present in our atmosphere that trap in heat almost like a blanket. Without the greenhouse effect the earth's average temperature would be approximately -20 degrees C (-4 F)!
5. greenhouse gas - are ranked in terms of how much they contribute to the greenhouse effect in terms of abundance and potency (for example, carbon dioxide is more abundant than methane, but methane is about 20X more potent of a greenhouse gas).
Anyway, the most abundant greenhouse gas is.... water vapor! which contributes 36-72%. Next up is carbon dioxide, 9-26%. Methane (farts! also carbon based) is 4-9%. And ozone is 3-7%. There are other greenhouse gases such as nitrous oxide and chlorofluorocarbons, but these 4 are the top contributors.
I'm giving a presentation on climate change this week, so will be attempting to break it down over the next few posts. Hopefully it's not too intense - for my 3 followers haha. Also, please comment! I'm not saying I'm right and am always looking for ideas/inputs!
To start off, some wicked fun definitions!
1. global warming - refers to global temperature increases we have experienced since the mid 20th century. Thought to be caused by human activity.
2. climate change - any change in the statistical distribution of weather. Can be either a change in the average or a change in the order of events surrounding the average. Can occur once, or in a cyclical pattern, over decades to millions of years. ex: El Nino, glacial and interglacial periods (ice ages), the Dust Bowl, etc.
3. global weirding - I just heard this the other day. an increase in severe or unusual environmental activity. This speaks to the fact that the earth isn't getting warmer everywhere. Some places may get colder, some may experience monsoons, and some drought.
4. greenhouse effect - caused because of the gases present in our atmosphere that trap in heat almost like a blanket. Without the greenhouse effect the earth's average temperature would be approximately -20 degrees C (-4 F)!
5. greenhouse gas - are ranked in terms of how much they contribute to the greenhouse effect in terms of abundance and potency (for example, carbon dioxide is more abundant than methane, but methane is about 20X more potent of a greenhouse gas).
Anyway, the most abundant greenhouse gas is.... water vapor! which contributes 36-72%. Next up is carbon dioxide, 9-26%. Methane (farts! also carbon based) is 4-9%. And ozone is 3-7%. There are other greenhouse gases such as nitrous oxide and chlorofluorocarbons, but these 4 are the top contributors.
Subscribe to:
Posts (Atom)