By Roz Pidcock
Of Earth's two vast ice sheets, Antarctica is perhaps the more mysterious. From the icy surface to the ocean below, there are several different ways the ice sheet is shrinking. How these processes compare is key to knowing how fast melting ice sheets are raising sea levels worldwide—and a new study may help to shed a bit more light.
Ice Sheets and Sea Level Rise
There is huge scientific interest in monitoring how the ice sheets are changing because when ice on land melts it drains into the ocean, causing sea levels to rise. Last week, a major review of how scientists' understanding of ice sheet melt has advanced since the last Intergovernmental Panel on Climate Change (IPCC) report in 2007.
But while Greenland is relatively well understood, at the other end of the planet in Antarctica, the picture is a little less clear, the report concludes.
Antarctic Ice Shelves
To understand how most of the ice is lost from Antarctica, a new study just published in Science looks to the ice shelves that surround 75 percent of the continent. Ice shelves are floating extensions of land ice that act as buttresses, stopping ice flowing from the interior straight out into the ocean.
Ice shelves line 75 percent of the Antarctic coastline. The biggest ones are the Ross and Ronne-Filchner ice shelves, marked here in red and dark blue. Source: National Snow and Ice Data Centre
Traditionally, scientists thought large chunks of solid ice breaking off the ice shelves was the main source of ice loss from Antarctica—a process known as iceberg calving. But there's another way. As the ocean below the ice shelves warms, the ice melts from the bottom up—something scientists call basal melting. With melting from both the top and bottom, some ice shelves are getting noticeably thinner, says the new study.
The paper looked at both processes of ice loss across 99.5 percent of Antarctica's ice shelves between 2003 and 2008. Overall, the scientists found basal melting caused 55 percent of ice loss, although they saw quite a lot of variation between regions. This makes bottom-up ice shelf melt the largest source of ice shelf loss in Antarctica. Previous studies have estimated the contribution to be more like 30 percent, or even as low as 10 percent.
"[T]he role of the Southern Ocean in controlling the evolution of ice shelves, thereby the evolution of the ice sheet as a whole, is more significant than estimated previously. This places more emphasis on understanding the evolution of the state of the Southern Ocean," said Professor Eric Rignot from the University of California Irvine. Rignot, the lead author on the paper, also called the study a "game-changer."
The scientists found smaller ice shelves melted more than large ones. Giant ice shelves like the Ross, Filchner and Ronne occupy two-thirds of the total ice shelf area but accounted for just 15 percent of melting. Half of the meltwater came from 10 smaller ice shelves occupying just eight percent of the total area.
An Uncertain Ice Sheet
If Antarctica melted completely, scientists estimate it could add about 58 metres to global sea level. At the moment, satellite data indicates the Antarctic ice sheet is losing ice but only at a rate of about 0.2 mm per year—more than three times slower than Greenland.
That's partly because different parts of the ice sheet are changing in different ways. Even though ice shelves in West Antarctica and the Antarctic Peninsula are melting and breaking apart, this doesn't contribute directly to sea level rise as they are already floating on water.
But their thinning accelerates ice flow from the many glaciers in the continent's interior, which does raise sea levels. Warmer air overlying the ice also causes melting on the surface. Nearly half of the ice shelves In East Antarctica are thinning too, according to the paper. But satellite data indicates the mass of ice in East Antarctica is growing overall thanks to an increase in snowfall.
Scientists warn there are still lots of uncertainties about these estimates. So monitoring the contribution of different processes—and how they're likely to change in the future—is critical for producing reliable projections of sea level rise.
Visit EcoWatch’s CLIMATE CHANGE page for more related news on this topic.
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By Sara Lindberg
Whether you've hit a workout plateau or you're just ready to turn things up a notch, adding more strenuous exercise — also known as high-intensity exercise — to your overall fitness routine is one way to increase your calorie burn, improve your heart health, and boost your metabolism.
However, to do it safely and effectively, there are some guidelines you should follow. Keep reading to learn more about the benefits of vigorous exercise and how to safely dial up the intensity of your workouts.
What Is Considered Strenuous Exercise?<p>When it comes to exercise, the intensity of how hard you work out is just as important as the duration of your exercise session. In general, exercise intensity is divided into three categories:</p><ul><li>low</li><li>moderate</li><li>vigorous or strenuous</li></ul><p>For an activity to be vigorous, you need to work at 70 to 85 percent of your maximum heart rate, according to the<a href="https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates" target="_blank"> American Heart Association</a>. Examples of vigorous exercise include:</p><ul><li>running</li><li>cycling at 10 mph or faster</li><li>walking briskly uphill with a heavy backpack</li><li>jumping rope</li></ul><p>Low to moderate exercise is easier to sustain for longer periods since you work below 70 percent of your maximum heart rate and, sometimes, well below that level.</p><p>To reap health benefits, the <a href="https://www.hhs.gov/fitness/be-active/physical-activity-guidelines-for-americans/index.html" target="_blank">Physical Activity Guidelines for Americans</a> recommends that people age 18 and older get one of the following:</p><ul><li><strong>150 minutes</strong> of moderate-intensity aerobic activity per week</li><li><strong>75 minutes</strong> of vigorous aerobic activity per week</li><li><strong>combination of both types</strong> of activity spread throughout the week</li></ul>
Strenuous Exercise Vs. Moderate Exercise<p>Increasing your exercise intensity is fairly simple to do. You can still participate in your favorite activities — just at a more vigorous pace.</p><p>One of the benefits of more strenuous exercise is that you can reap the same rewards as moderate-intensity exercise but in less time. So, if time is of the essence, doing a more strenuous 20-minute workout can be just as beneficial as doing a slower 40-minute workout session.</p><p>Here are some examples of <a href="https://www.cdc.gov/nccdphp/dnpa/physical/pdf/pa_intensity_table_2_1.pdf" target="_blank">strenuous vs. moderate exercise<span></span></a>.</p><table><tbody><tr><th>Moderate intensity</th><th>Strenuous intensity</th></tr><tr><td>bicycling at less than 10 mph</td><td>bicycling at more than 10 mph</td></tr><tr><td>walking briskly</td><td>running, or hiking uphill at a steady pace</td></tr><tr><td>jog-walk intervals</td><td>water jogging/running</td></tr><tr><td>shooting baskets in basketball</td><td>playing a basketball game</td></tr><tr><td>playing doubles tennis</td><td>playing singles tennis</td></tr><tr><td>raking leaves or mowing the lawn</td><td>shoveling more than 10 lbs. per minute, digging ditches</td></tr><tr><td>walking stairs</td><td>running stairs</td></tr></tbody></table>
Benefits of Vigorous Exercise<p>Besides being more efficient, turning up the heat on your fitness sessions can benefit your health in a variety of ways. Let's take a closer look at some of the evidence-based benefits of a higher intensity workout.</p><ul><li><strong>Higher calorie burn.</strong> According to the <a href="https://www.acefitness.org/education-and-resources/professional/expert-articles/5008/7-things-to-know-about-excess-post-exercise-oxygen-consumption-epoc/?utm_source=Rakuten&utm_medium=10&ranMID=42334&ranEAID=TnL5HPStwNw&ranSiteID=TnL5HPStwNw-hYlKnAcfzfixAUsvnO6Ubw" target="_blank">American Council on Exercise</a>, working out at a higher intensity requires more oxygen, which burns more calories. It also contributes to excess post-exercise oxygen consumption (EPOC) or the "afterburn effect" that allows you to continue burning calories even after you finish working out. This means your metabolism will stay elevated for longer after a vigorous exercise session.</li><li><strong>More weight loss.</strong> A <a href="https://www.healthline.com/health-news/interval-workouts-will-help-you-lose-weight-more-quickly" target="_blank">higher calorie burn</a> and an elevated metabolism will help you lose weight more quickly than doing low- or moderate-intensity exercise.</li><li><strong>Improved heart health.</strong> According to a <a href="https://www.ncbi.nlm.nih.gov/pubmed/16377300" target="_blank">2012 study</a>, high- and moderate-intensity exercise appears to offer low chance of cardiovascular events, even in those with heart disease. Cardiovascular benefits may include improvements in:<ul><li><a href="https://www.healthline.com/health/diastole-vs-systole" target="_blank">diastolic blood pressure</a></li><li><a href="https://www.healthline.com/nutrition/15-ways-to-lower-blood-sugar#TOC_TITLE_HDR_1" target="_blank">blood sugar control</a></li><li>aerobic capacity</li></ul></li><li><strong>Improved mood.</strong> High-intensity exercise may also boost your mood. According to a large <a href="https://www.jstage.jst.go.jp/article/jpts/27/4/27_jpts-2014-736/_article" target="_blank">2015 study</a> that analyzed the data of more than 12,000 participants, researchers found a significant link between strenuous exercise and fewer depressive symptoms.</li><li><strong>Lower risk of mortality.</strong> According to a 2015 <a href="https://www.ncbi.nlm.nih.gov/pubmed/25844882" target="_blank">study</a>, researchers found that vigorous activity may be key to avoiding an early death. The study, which followed 204,542 people for more than 6 years, reported a 9 to 13 percent decrease in mortality for those who increased the intensity of their exercise sessions.</li></ul>
How to Measure Exercise Intensity<p>So, how do you know for sure that you're exercising at a strenuous level? Let's look at three ways to measure the intensity of your physical activity.</p><h3>1. Your heart rate</h3><p>Monitoring your heart rate is one of the most reliable methods for measuring exercise intensity. Exercising at 70 to 85 percent of your maximum heart rate qualifies as vigorous exercise intensity.</p><blockquote><strong><strong>WHAT IS YOUR MAXIMUM HEART RATE?</strong></strong>Your maximum heart rate is the fastest your heart can safely beat. To find out what your maximum heart rate is you need to subtract your age from 220. For example, for a 40-year-old person: <ul><li>220 bpm (beats per minute) minus age</li><li>220 – 40 = 180 bpm</li></ul>To work out at a vigorous pace, you'll want to exercise within 70 to 85 percent of your maximum heart rate. For example: <ul><li>180 x 0.70 (70 percent) = 126</li><li>180 x 0.85 (85 percent) = 153</li></ul>For a 40-year-old person, a vigorous training range is 126 to 153 bpm.<br></blockquote><p>You can check your heart rate while you're working out by wearing a heart rate monitor or <a href="https://www.healthline.com/health/how-to-check-heart-rate" target="_blank">taking your pulse</a>.</p>
How to Add Vigorous Activity to Your Workout<p>Adding strenuous activity to your weekly workout routine requires some careful planning. Fortunately, many of the activities that you do at a moderate level can easily be performed at a higher intensity.</p><p>One way of incorporating vigorous aerobic activity into your routine is to do a <a href="https://www.healthline.com/nutrition/benefits-of-hiit" target="_blank">high-intensity interval training (HIIT)</a> workout. This type of workout combines short bursts of intense activity — typically performed at 80 to 95 percent of your maximum heart rate — with recovery periods at 40 to 50 percent maximum heart rate.</p><p>To sustain this level of training, consider following a 2:1 work to rest ratio. For example, a <a href="https://www.healthline.com/health/treadmill-weight-loss#hiit" target="_blank">treadmill workout </a>or outdoor running session could include:</p><ul><li>running at 9 to 10 mph for 30 seconds</li><li>followed by walking at 3 to 4 mph for 60 seconds</li><li>alternating this work-to-rest ratio for 20 to 30 minutes</li></ul><p>Playing a fast-paced sport like soccer, basketball, or racquetball is another effective way to add strenuous activity to your fitness routine. Participating in <a href="https://www.healthline.com/health/benefits-of-a-spin-class" target="_blank">cycling classes</a> or swimming laps are other ways to build more strenuous exercise into your workouts.</p>
Safety Tips<p>Before you turn up the intensity on your workouts, it's important to keep the following safety tips in mind.</p><h3>Check with your doctor</h3><p>If you have a health condition or you haven't been active in a while, make sure you talk to your doctor before you start a high-intensity exercise routine. Your doctor can advise you on a safe level of exercise or how to become more active in the safest way possible.</p><h3>Build up the intensity slowly</h3><p>Going from low- or moderate-intensity workouts to vigorous exercise requires time and patience. While you may be ready to jump in with both feet, the safest way to add more vigorous exercise is to do it in bite-size increments. Pushing yourself too quickly can result in injuries and burnout.</p><p>For example:</p><ul><li><strong>Week 1:</strong> Swap out one moderate-paced cardio session for a HIIT workout.</li><li><strong>Week 2:</strong> Swap one moderate-paced session with a HIIT workout, and also add a circuit strength training session to your weekly routine.</li><li><strong>Week 3 and 4: </strong>Repeat weeks 1 and 2 before you start adding more high-intensity exercise to your weekly routine.</li></ul><p>It's also a good idea to space out your vigorous workouts throughout the week. Try not to do two strenuous sessions back-to-back.</p><h3>Don't forget the recovery time</h3><p>Your body requires more time to recover from a vigorous workout compared to a low- or moderate-intensity session.</p><p>To help your body recover, make sure to always include a cooldown and <a href="https://www.healthline.com/health/exercise-fitness/static-stretching" target="_blank">stretch routine</a> after strenuous physical activity.</p><h3>Stay hydrated</h3><p><a href="https://www.healthline.com/nutrition/7-health-benefits-of-water" target="_blank">Staying hydrated</a> is especially important when you're exercising hard. Not drinking enough fluids can affect the quality of your workout and make you feel tired, lethargic, or dizzy. It may even lead to <a href="https://www.healthline.com/health/dehydration-headache" target="_blank">headaches</a> and <a href="https://www.healthline.com/health/pain-relief/how-to-stop-leg-muscle-cramps" target="_blank">cramps</a>.</p>
The Bottom Line<p>Turning up the intensity of your workout sessions can be an effective way of boosting your overall health and fitness. It's also an easy way to save time when trying to fit a workout into your day.</p><p>To play it safe, always start slow and pay attention to how your body feels.</p><p>While vigorous exercise offers many health benefits, it's not appropriate for everyone. If you have a health condition or you haven't been active in a while, make sure to talk with your doctor before working out at a more strenuous level.</p>
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By Jeffrey Miller
In January 2015, food sales at restaurants overtook those at grocery stores for the first time. Most thought this marked a permanent shift in the American meal.
Solving the Age-Old Problem of Spoiled Cheese<p>People have eaten pasta and cheese together for hundreds of years. Clifford Wright, the doyen of Mediterranean food history, says <a href="http://www.cliffordawright.com/caw/food/entries/display.php/topic_id/16/id/105/" target="_blank">the first written recipe</a> for macaroni and cheese was created in the court of the king of Naples in the 13th century, while <a href="https://food52.com/blog/9916-the-history-of-macaroni-and-cheese" target="_blank">the first reference</a> in an English language cookbook likely appeared in Elizabeth Raffald's 1769 book "The Experienced English Housekeeper."</p><p><span></span>An internet search for macaroni and cheese recipes will turn up over 5 million hits, but many still prefer to get theirs in a box – the kind with pasta that comes in shapes ranging from shells to Pokemon characters, accompanied by a packet of powdered cheese sauce.</p><p>Boxed macaroni and cheese was one outcome of the quest for ways to keep cheese longer. Some cheese gets better as it ages – a well-aged cheddar is one of life's delights – but once most cheeses hit their prime, <a href="https://www.dairyfoods.com/articles/91548-how-to-maximize-cheese-shelf-life" target="_blank">they tend to quickly go bad</a>. Before household refrigeration became common, many retailers wouldn't even stock cheese in the summer because it spoiled so quickly.</p><p>Processed cheese solved this age-old problem.</p>
When Natural Was Nasty<p>Today, food that's simple, pure and natural is <a href="https://theconversation.com/how-was-french-cuisine-toppled-as-the-king-of-fine-dining-66667" target="_blank">all the craze</a>, while <a href="https://apnews.com/c06a1200807c4b82a03452d08d480692" target="_blank">disdain for processed foods</a> is practically a credo among sophisticated consumers.</p><p>But when Kraft's different forms of processed cheese came out, they found widespread acceptance despite their strange textures. The fact that it wasn't natural didn't seem to bother consumers at all. In fact, as international food historian Rachel Laudan <a href="https://online.ucpress.edu/gastronomica/article/1/1/36/93394/A-Plea-for-Culinary-Modernism-Why-We-Should-Love" target="_blank">has noted</a>, back then, "natural was something quite nasty." She describes fresh milk as warm and "unmistakably a bodily secretion." Throughout the history of cookery, most recipes aimed to transform an unappetizing raw product into something delightful and delectable.</p><p>So for most consumers, processed foods were a godsend. They kept well, tended to be easily digestible and, most importantly, they tasted good. Many of them could be easily prepared, freeing women from spending entire days cooking and giving them more time to pursue professions and avocations.</p><p>In some ways, processed foods were also healthier. They could be fortified with vitamins and minerals, and, in an era before everyone had access to mechanical refrigeration, the fact that they kept well meant consumers were less likely to contract diseases from spoiled, rotten foods. Pasteurization of dairy products virtually <a href="https://www.the-scientist.com/foundations/rethinking-raw-milk--1918-65126" target="_blank">eliminated diseases like undulant fever</a>, while foods processed and canned in large factories were less likely to harbor food-borne illnesses that could crop up due to faulty or improperly sanitized equipment used by home canners.</p>
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