斯韦茨冰川下的减速带可以帮助减缓冰川流入海洋的速度

　　

　　旧金山——大多数关于思韦茨冰川的消息都是坏消息。思韦茨冰川是佛罗里达州大小的一块冰，正在融化，目前对全球海平面上升的贡献约为4%。但是一些好消息可能已经出现了。

　　12月12日，冰川学家科恩·霍夫斯泰德在美国地球物理联合会秋季会议的新闻发布会上说，对斯韦茨河上游一段河床下的地震调查显示，南极冰川下有高耸的地面，其高度与曼哈顿的天际线相当。这些崎岖不平的隆起可能会阻碍冰川的下腹，减缓冰川流向海洋的速度，减缓全球海平面的上升。

　　

　　.email-conversion {

　　border: 1px solid #ffcccb;

　　color: white;

　　margin-top: 50px;

　　background-image: url("/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg");

　　padding: 20px;

　　clear: both;

　　}

　　]]>

　　*{color:var(--zephr-color-text-main)}.zephr-registration-form-relative-container{position:relative}.zephr-registration-form-flex-container{display:flex}.zephr-registration-form-input.svelte-blfh8x{display:block;width:100%;height:calc(var(--zephr-input-height) * 1px);padding-left:8px;font-size:16px;border:calc(var(--zephr-input-borderWidth) * 1px) solid var(--zephr-input-borderColor);border-radius:calc(var(--zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(--zephr-color-text-main);background-color:#fff;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-input.svelte-blfh8x::placeholder{color:var(--zephr-color-background-tinted)}.zephr-registration-form-input-checkbox.svelte-blfh8x{width:auto;height:auto;margin:8px 5px 0 0;float:left}.zephr-registration-form-input-radio.svelte-blfh8x{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-input-color[type="color"].svelte-blfh8x{width:50px;padding:0;border-radius:50%}.zephr-registration-form-input-color[type="color"].svelte-blfh8x::-webkit-color-swatch{border:none;border-radius:50%;padding:0}.zephr-registration-form-input-color[type="color"].svelte-blfh8x::-webkit-color-swatch-wrapper{border:none;border-radius:50%;padding:0}.zephr-registration-form-input.disabled.svelte-blfh8x,.zephr-registration-form-input.disabled.svelte-blfh8x:hover{border:calc(var(--zephr-input-borderWidth) * 1px) solid var(--zephr-input-borderColor);background-color:var(--zephr-color-background-tinted)}.zephr-registration-form-input.error.svelte-blfh8x{border:1px solid var(--zephr-color-warning-main)}.zephr-registration-form-input-label.svelte-1ok5fdj.svelte-1ok5fdj{margin-top:10px;display:block;line-height:30px;font-size:12px;color:var(--zephr-color-text-tinted);font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj{display:block}.zephr-registration-form-button.svelte-17g75t9{height:calc(var(--zephr-button-height) * 1px);line-height:0;padding:0 20px;text-decoration:none;text-transform:capitalize;text-align:center;border-radius:calc(var(--zephr-button-borderRadius) * 1px);font-size:calc(var(--zephr-button-fontSize) * 1px);font-weight:normal;cursor:pointer;border-style:solid;border-width:calc(var(--zephr-button-borderWidth) * 1px);border-color:var(--zephr-color-action-tinted);transition:backdrop-filter 0.2s, background-color 0.2s;margin-top:20px;display:block;width:100%;background-color:var(--zephr-color-action-main);color:#fff;position:relative;overflow:hidden;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-button.svelte-17g75t9:hover{background-color:var(--zephr-color-action-tinted);border-color:var(--zephr-color-action-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled{background-color:var(--zephr-color-background-tinted);border-color:var(--zephr-color-background-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled:hover{background-color:var(--zephr-color-background-tinted);border-color:var(--zephr-color-background-tinted)}.zephr-registration-form-text.svelte-i1fi5{font-size:19px;text-align:center;margin:20px auto;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-divider-container.svelte-mk4m8o{display:flex;align-items:center;justify-content:center;margin:40px 0}.zephr-registration-form-divider-line.svelte-mk4m8o{height:1px;width:50%;margin:0 5px;background-color:var(--zephr-color-text-tinted);;}.zephr-registration-form-divider-text.svelte-mk4m8o{margin:0 12px;color:var(--zephr-color-text-main);font-size:14px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);white-space:nowrap}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(--zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message.svelte-179421u{text-align:center;padding:10px 30px;border-radius:5px;font-size:15px;margin-top:10px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message-title.svelte-179421u{font-weight:bold;margin-bottom:10px}.zephr-registration-form-response-message-success.svelte-179421u{background-color:#baecbb;border:1px solid #00bc05}.zephr-registration-form-response-message-error.svelte-179421u{background-color:#fcdbec;border:1px solid #d90c00}.zephr-registration-form-social-sign-in.svelte-gp4ky7{align-items:center}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7{height:55px;padding:0 15px;color:#000;background-color:#fff;box-shadow:0px 0px 5px rgba(0, 0, 0, 0.3);border-radius:10px;font-size:17px;display:flex;align-items:center;cursor:pointer;margin-top:20px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7:hover{background-color:#fafafa}.zephr-registration-form-social-sign-in-icon.svelte-gp4ky7{display:flex;justify-content:center;margin-right:30px;width:25px}.zephr-form-link-message.svelte-rt4jae{margin:10px 0 10px 20px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-recaptcha-tcs.svelte-1wyy3bx{margin:20px 0 0 0;font-size:15px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-recaptcha-inline.svelte-1wyy3bx{margin:20px 0 0 0}.zephr-registration-form-progress-bar.svelte-8qyhcl{width:100%;border:0;border-radius:20px;margin-top:10px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-bar{background-color:var(--zephr-color-background-tinted);border:0;border-radius:20px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-value{background-color:var(--zephr-color-text-tinted);border:0;border-radius:20px}.zephr-registration-progress-bar-step.svelte-8qyhcl{margin:auto;color:var(--zephr-color-text-tinted);font-size:12px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-progress-bar-step.svelte-8qyhcl:first-child{margin-left:0}.zephr-registration-progress-bar-step.svelte-8qyhcl:last-child{margin-right:0}.zephr-registration-form-input-error-text.svelte-19a73pq{color:var(--zephr-color-warning-main);font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-input-select.svelte-19a73pq{display:block;appearance:auto;width:100%;height:calc(var(--zephr-input-height) * 1px);font-size:16px;border:calc(var(--zephr-input-borderWidth) * 1px) solid var(--zephr-color-text-main);border-radius:calc(var(--zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(--zephr-color-text-main);background-color:#fff;padding:10px}.zephr-registration-form-input-select.disabled.svelte-19a73pq{border:1px solid var(--zephr-color-background-tinted)}.zephr-registration-form-input-select.unselected.svelte-19a73pq{color:var(--zephr-color-background-tinted)}.zephr-registration-form-input-select.error.svelte-19a73pq{border-color:var(--zephr-color-warning-main)}.zephr-registration-form-input-textarea.svelte-19a73pq{background-color:#fff;border:1px solid #ddd;color:#222;font-size:14px;font-weight:300;padding:16px;width:100%}.zephr-registration-form-input-slider-output.svelte-19a73pq{margin:13px 0 0 10px}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(--zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.spin.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 2s 0s infinite linear}.pulse.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 1s infinite steps(8)}@keyframes svelte-1cj2gr0-spin{0%{transform:rotate(0deg)}100%{transform:rotate(360deg)}}.zephr-registration-form-checkbox.svelte-1gzpw2y{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-checkbox-label.svelte-1gzpw2y{display:flex;align-items:center;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-checkmark.svelte-1gzpw2y{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid var(--zephr-color-text-main);border-radius:6px;margin-right:12px;cursor:pointer}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y{border-color:#009fe3}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y:after{content:"";position:absolute;width:6px;height:13px;border:solid #009fe3;border-width:0 2px 2px 0;transform:rotate(45deg);top:3px;left:8px;box-sizing:border-box}.zephr-registration-form-checkmark.disabled.svelte-1gzpw2y{border:1px solid var(--zephr-color-background-tinted)}.zephr-registration-form-checkmark.disabled.checked.svelte-1gzpw2y:after{border:solid var(--zephr-color-background-tinted);border-width:0 2px 2px 0}.zephr-registration-form-checkmark.error.svelte-1gzpw2y{border:1px solid var(--zephr-color-warning-main)}.zephr-registration-form-input-radio.svelte-1qn5n0t{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-radio-label.svelte-1qn5n0t{display:flex;align-items:center;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-radio-dot.svelte-1qn5n0t{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid #ebebeb;border-radius:50%;margin-right:12px}.checked.svelte-1qn5n0t{border-color:#009fe3}.checked.svelte-1qn5n0t:after{content:"";position:absolute;width:17px;height:17px;background:#009fe3;background:linear-gradient(#009fe3, #006cb5);border-radius:50%;top:2px;left:2px}.disabled.checked.svelte-1qn5n0t:after{background:var(--zephr-color-background-tinted)}.error.svelte-1qn5n0t{border:1px solid var(--zephr-color-warning-main)}.zephr-form-link.svelte-64wplc{margin:10px 0;color:#6ba5e9;text-decoration:underline;cursor:pointer;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-form-link-disabled.svelte-64wplc{color:var(--zephr-color-text-main);cursor:none;text-decoration:none}.zephr-registration-form-google-icon.svelte-1jnblvg{width:20px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(--zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(--zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}]]>

　　* {

　　color: #FFFFFF;

　　font-weight: bold

　　font: 25px;

　　}

　　.zephr-registration-form-progress-bar.svelte-8qyhcl {

　　width: 100%;

　　border: 0;

　　border-radius: 20px;

　　margin-top: 10px;

　　display: none;

　　}

　　.zephr-registration-form-response-message-title.svelte-179421u {

　　font-weight: bold;

　　margin-bottom: 10px;

　　display: none;

　　}

　　.zephr-registration-form-response-message-success.svelte-179421u {

　　background-color: #8db869;

　　border: 1px solid #8db869;

　　color: white;

　　margin-top: -0.2rem;

　　}

　　.zephr-registration-form-text.svelte-i1fi5:nth-child(1){

　　font-size: 18px;

　　text-align: center;

　　margin: 20px auto;

　　font-family: var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);

　　color: white;

　　}

　　.zephr-registration-form-text.svelte-i1fi5:nth-child(5){

　　font-size: 18px;

　　text-align: left;

　　margin: 20px auto;

　　font-family: var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);

　　color: white;

　　}

　　.zephr-registration-form-text.svelte-i1fi5:nth-child(7){

　　font-size: 18px;

　　text-align: left;

　　margin: 20px auto;

　　font-family: var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);

　　color: white;

　　}

　　.zephr-registration-form-text.svelte-i1fi5:nth-child(9){

　　font-size: 18px;

　　text-align: left;

　　margin: 20px auto;

　　font-family: var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);

　　color: white;

　　}

　　.zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj {

　　display: none;

　　color: white;

　　}

　　.zephr-registration-form-input.disabled.svelte-blfh8x, .zephr-registration-form-input.disabled.svelte-blfh8x:hover {

　　border: calc(var(--zephr-input-borderWidth) * 1px) solid var(--zephr-input-borderColor);

　　background-color: white;

　　}

　　.zephr-registration-form-checkbox-label.svelte-1gzpw2y {

　　display: flex;

　　align-items: center;

　　font-family: var(--zephr-typography-body-font), var(--zephr-typography-body-fallbackFont);

　　color: white;

　　font-size: 20px;

　　margin-bottom: -20px;

　　}]]>

　　Glaciers flow somewhat like rivers, but much slower. Where Thwaites outlets into the ocean, it connects to a floating shelf of ice that braces and partially restrains the glacier. That ice shelf was once pinned upon an underwater mountain, which helped stabilize it (SN: 12/13/21). But now the shelf is so deteriorated that it’s basically unhitched, Erin Pettit, a glaciologist at Oregon State University in Corvallis, said at the news event.

　　Fortunately, though, the glacier “is not going to suddenly flow off land,” thanks partly to what’s been discovered upstream, said Pettit, who was not involved in the discovery.

　　More than 70 kilometers inland from Thwaites’ ice shelf, Hofstede and his colleagues conducted a seismic survey to probe the glacier’s underbelly. The team attached a 1.5-kilometer-long daisy-chain of seismometers to a vehicle equipped with a vibrating plate. Then they drove a roughly 200-kilometer-long stretch of the glacier, using the plate to generate seismic waves and the seismometers to record the waves’ reflectance off layers of ice and earth below. “It’s almost like radar,” said Hofstede, of the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research in Bremerhaven, Germany.

　　The seismic waves revealed rises under Thwaites that are 10 to 20 kilometers long and toothed with blocks of sediment. These blocks stood up to 100 meters tall above the rises and stretched for up to several kilometers horizontally.

　　The data showed that the upstream faces of these blocks appear to be under greater pressure than their downstream sides, and that there might be layers of deformed ice within the glacier above the rises. Hofstede hypothesizes that the rises and blocks are slowing Thwaites’ flow as its ice presses against them.

　　Using computers to simulate the flow of Thwaites glacier shows that “it gets hung up on tall features,” said glaciologist Ben Smith of the University of Washington in Seattle, who was not involved in the work.

　　The rises are probably related to a rift system, an area where tectonic forces have pulled the ground apart, Hofstede said. Under Thwaites, these rifts run roughly perpendicular to the glacier’s ice flow, sort of like speed bumps on a street.

　　The findings will allow for more nuanced simulations of the glacier’s evolution, Hofstede said, which are crucial for understanding rates of sea level rise.

　　?