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Does climate change result in an increase of wildfires?

As the temperatures get warmer and the days start getting longer, you may be excited for the summer season to start. However, the arrival of summer also means dryer weather, water shortages, and wildfires.

Poor air quality in Vancouver due to the raging wildfires.         Photo Source: flickr

Wildfires can occur anywhere, but are most prevalent in the forests of Canada, the United States, Europe, and throughout the vegetated areas of Australia and South Africa. These wildfires are capable of destroying entire areas of up to 2.5 million hectare per year in Canada and can travel at speeds of 23 kilometers per hour! The main causes of wildfires are lightning and humans (surprise!), with lightning caused fires making up 45% of all fires and 55% of all fires being connected to human activities.

Historical wildfires across Canada. Photo Source: Natural Resources Canada

Although lightning caused wildfires occur naturally every year and are essential for the environment, wildfires should still be a concern for all of us. The smog that visits Vancouver every summer seems more severe year after year, could climate change be increasing the occurrence of wildfires?

According to science, climate change does result in an increase of wildfires. Climate change is the result of human activities, such as, fossil fuel burning, which produces large quantities of carbon dioxide. Just like methane and ozone, carbon dioxide is also a heat-trapping molecule, which you might know as a greenhouse gas. With greenhouse gas concentrations increasing, the heat radiated from earth cannot leave earth’s atmosphere. Over 90 percent of this trapped heat accumulates in the ocean and as a consequence, ocean heat contents rise and cause increases in global ocean temperatures. The increase in global heat content also causes ice to melt and sea levels to rise.

Global ocean heat content (OHC) for the top 2000 m of the ocean. Uncertainty estimates are shown in pink. Source: Science Advances

Aside from an increase in global ocean temperatures and higher sea levels, temperatures on land are also raised due to the trapping of heat by greenhouse gases. This results in more droughts and dryer weather, which are perfect conditions for wildfires to pick up.

So, other than knowing the reason for an increase in wildfires, how can we do our best to prevent wildfires from occurring?

First of all, always obey fire bans and signs that indicate the wildfire danger ratings. Next, never leave a campfire unattended & completely extinguish the campfire when leaving the area. Furthermore, any smoking material should be properly disposed of and most importantly, be sure to report any signs of wildfires.

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Posted on March 27, 2019 by in Uncategorized

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New technology might allow mammals to have super-visual capabilities in the future

Radio waves, gamma rays, visible light, and all the other parts of the electromagnetic spectrum are electromagnetic radiation. However, a typical mammalian eye can only respond to visible light, which is a small portion (<1%) of the electromagnetic spectrum. But a recent study shows a new technology that may enable humans to sense near-infrared light.

The electromagnetic spectrum. Retrieved from Wikipedia Common.

The group of Professor Tian Xue from the University of Science and Technology of China and the group of Professor Gang Han from the University of Massachusetts State University have for the first time achieved the naked-eye infrared light perception in mice. Mice were able to see near-infrared light after being injected with special nanoparticles into their eyes. The special nanoparticles named pbUCNPs can anchor tightly on the retinal photoreceptors of mice and convert near-infrared light into visible green light. Additionally, these nanoparticles can stay in the eye for over two months without any obvious side effect.

The injection of the nanoparticles into the eyes of the mice. Image created by Ma et al.

Xue said: “This research breaks through the limitations of traditional near-infrared spectroscopy and develops a naked-eye passive infrared vision expansion technology, suggesting that humans have the potential for super-visual capabilities.”

To prove that the injected mice could see near-infrared light, the scientists did two experiments.

One experiment called pupillary light reflex. The pupillary light reflex gives the constriction of pupils in response to stimulation of eyes by light. The researchers shined near-infrared light into the eyes of injected and non-injected mice. The pupils of the injected mice constricted, while the non-injected mice showed no response.

pbUNCPs allow for detection of near-infrared (NIR) light. (A) Images show only the mouse injected with pbUCNPs gives a reflex when exposed to NIR light (980 nm), indicating that pbUCNP-injected mice are able to sense NIR light. (B) The curve shows the more intensive the NIR light is, the greater the pupil constriction response. Data are mean±SD. (Ma et al., 2019)

In the second experiment, as mice prefer to stay in the dark, the researches designed a box with two connected compartments. One compartment was completely dark, and the other was illuminated with near-infrared light. Scientists observed that the injected mice spent more time in the dark compartment, while the non-injected mice spent similar amounts of time in both compartments. 

The set-up of the Light-Dark Box. (Ma et al., 2019)

pbUCNP-injected mice recognize and respond to NIR light. Control mice and those injected with pbUCNPs responded to visible light (525 nm). However, when the light was in the NIR range (980 nm), only mice injected with pbUCNPs responded. Data are mean±SD. (Ma et al., 2019)

These two experiments proved that the injected mice perceived near-infrared light. Moreover, the scientists showed that the nanoparticles would not affect the normal vision of the injected mice.

This technique can potentially be applied to humans not only for generating super vision but also for repairing visible spectrum defects, such as colour blindness. 

 

 

 

Wenxin Zhao

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Posted on March 22, 2019 by in Biological Sciences

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Forensic: How to Measure the Unknown Time of Death from Only Bone and Hair Remains

Typically, TV forensic shows, such as CSI and Bones, portray how forensic cases are fast and easy to solve within a couple of episodes. However, that is not true. Unlike in forensic shows, forensic cases take a long time to solve in real life, due to challenges that investigators have to face.

One of the challenges that criminal investigators have to solve is to determine the post-mortem interval (PMI) from decomposed skeletons. Post-mortem interval is the time after someone has died, which is important when the cause of death is unknown. Usually, medical assessment of corpses can determine the PMI after the body is dead for the first few days. However, when the victim’s bones and hairs are found after a few years, the accuracy of the PMI lowers. Therefore, new method is required to provide a more accurate estimation of the extended time of death.

Currently, there are numerous studies that use different methods for solving the PMI. Many methods include analyzing soil chemistry and insects at the crime scene. Since these methods could be complementary to each other, the scientists in Switzerland believe that combining these methods would improve the long-term PMI estimate, while illustrating how the crime scene could have occurred. Therefore, the Swiss scientists have attempted to use five different approaches simultaneously to estimate the PMI of the bone and hair remains. Once the soil, bone, and hair samples are collected from the Swiss forest, the scientists use five different approaches for analyses, which include using radiocarbon dating, analyzing pH and soil chemistry, counting and classifying nematodes and mites, and sequencing DNA of soil micro-eukaryotes.

 

After analyzing the findings, the scientists are able to propose a possible PMI, as well as the crime scene. First of all, the radiocarbon dating determines that the bones belong to a young adult male. Secondly, chemical, nematodes, and micro-eukaryotic analyses suggest that the remains have been partly decomposed in the forest for at least 8-9 months. Finally, the evidence from mites suggests that the corpse is partly decomposed in a separate confined place, because these mite species are only found in confined environment. Therefore, the suspect(s) could have allowed the corpse to decompose in a confined area before relocating it to the Swiss forest. As a result, the PMI of the dead victim appears to be at least 8-12 months before the body is discovered.

The skeleton that is found in a Swiss forest. Ildikó Szelecz, Sandra Lösch, Christophe V. W. Seppey, Enrique Lara, David Singer, Franziska Sorge1, Joelle Tschui, M. Alejandra Perotti & Edward A. D. Mitchell, Source, Creative Commons Attribution 4.0 International Licence

Overall, the study shows that using five approaches simultaneously in a forensic case study can estimate the PMI, while illustrating a possible crime scene of how the victim could have died. Moreover, all of the approaches can be complementary with each other, in order to provide more evidence from scarce remains. In conclusion, it is possible to further develop this technique in order to estimate PMI in other forensic cases.

Update: Blog post has been revised on 2019, Feb 15th.

Reference

Rasmussen College. How Accurate are Crime Shows on TV? Debunking 7 Common Myths. https://www.rasmussen.edu/degrees/justice-studies/blog/crime-show-myths-debunked-forensic-experts-tell-what-life-is-real/

Keele University. Chemical Ecology. PMI in Forensic Entomology. https://www.keele.ac.uk/chemicalecology/projects/pmi/

American Council on Science and Health. How Chemistry, Microbiology Could Help Catch A Killer. https://www.acsh.org/news/2018/01/18/how-chemistry-microbiology-could-help-catch-killer-12422 .

Szelecz, I.; Lösch, S.; Seppey, C. V. W.; Lara, E.; Singer, D.; Sorge, F.; . . . Mitchell, E. A. D. . Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval. Scientific Reports. [Online] 2018, 8(1), 25. doi:10.1038/s41598-017-18179-z.

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Posted on January 29, 2019 by in Biological Sciences, Science in the News, Uncategorized

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